Accountability verification

Configuration management-identification, control (including problem reports), status accounting, verification audit... 

In order to make a meaningfiil statistical evaluation of the results of accountancy verifications, the inspector s measurements must be planned in a way, which will provide independent estimates of the overall measurement uncertainties. All factors influencing these uncertainties must be considered, such as the material type and form, the sampling procedure, and the measurement method. According to theory and experience, the inspectorate detection... 

The sample size for a stratum defines the number of items to be verified in order to be able to draw conclusions about the total population. The total sample size can then be allocated among the accountancy verification methods for gross, partial and bias defects (IAEA 1998a Jaech and Russell 1991). The uncertainty values generally used are the verification performance estimates for the given facility and strata. The International Target Values could serve as a substitute (IAEA 2001). 

Laboratory Analysis for Nuclear Material Accountability Verifications... 

The concept of IAEA s safeguards analytical services (Lopez-Menchero et al. 1976) foresaw that the agency would establish and operate a fully equipped safeguards analytical laboratory (SAL). The analytical capability of SAL was to be such that samples taken from any key measurement point of the fuel cycle could be analyzed and that the results of these analyses would meet the requirements of safeguards accounting verification. 

Although the technique is more expensive than radiometry, mass spectrometry is, however, the preferred method for IDA of samples of nuclear materials taken for accountability verifications. Traditionally, separated or highly enriched isotopes, absent from the samples or only present as minor isotopes, such as Pu, Pu or Th were used as spike material in isotope dilution mass spectrometry. IDMS is the standard operator method for the accountability of nuclear materials in input solutions of irradiated nuclear fuels. The method involves taking a representative sample from the input accountability tank and diluting it accurately 100-1,000-fold in a heavily shielded cell. A portion of the diluted solution is transferred to... 

IAEA (2003) International nuclear verification series no. 1 (revised), ISBN 92-0-109403-5 IAEA (2004) Destructive analysis and evaluation services for nuclear material accountability verifications,... 

Taking into account that it is necessary to make vary the flaw detector settings during the main part of the verifications, the total number of verifications is rather important. So, Technical Center for Mechanical Industries (CETIM) began the development of an electronic system enabling to benefit of the current possibilities of generation of synthesised radio frequency signals and help of personal computer for operator assistance and calculation. 

Because of the various characteristics of composite laminates, it is difficult to determine a strength criterion in which all failure modes and their interactions are properly accounted for. Moreover, the verification of a proposed strength criterion is greatly complicated by scatter in measured strengths caused by inconsistent processing techniques (that... 

S. G. Mueller, R. Eckstein, D. Hofmann, L. Kadinski, P. Kaufmann, M. Koelbl, E. Schmitt. Modelling of the PVT-SiC bulk growth process taking into account global heat transfer, mass transport and heat of crystal-Uzation and results on its experimental verification. Mater Sci Eorum 0 51, 1998. 

In their broadest application, CRMs are used as controls to verify in a direct comparison the accuracy of the results of a particular measurement parallel with this verification, traceability may be demonstrated. Under conditions demonstrated to be equal for sample and CRM, agreement of results, e.g. as defined above, is proof. Since such possibilities for a direct comparison between samples and a CRM are rare, the user s claims for accuracy and traceability have to be made by inference. Naturally, the use of several CRMs of similar matrix but different analyte content will strengthen the user s inference. Even so, the user stiU has to assess and account for all uncertainties in this comparison of results. These imcertainty calculations must include beyond the common analytical uncertainty budget (i) a component that reflects material matrix effects, (2) a component that reflects differences in the amount of substance determined, (3) the uncertainty of the certified or reference value(s) used, and 4) the uncertainty of the comparison itself AU this information certainly supports the assertion of accuracy in relation to the CRM. However, the requirement of the imbroken chain of comparisons wiU not be formally fulfilled. 

Monomers employed in a polycondensation process in respect to its kinetics can be subdivided into two types. To the first of them belong monomers in which the reactivity of any functional group does not depend on whether or not the remaining groups of the monomer have reacted. Most aliphatic monomers meet this condition with the accuracy needed for practical purposes. On the other hand, aromatic monomers more often have dependent functional groups and, thus, pertain to the second type. Obviously, when selecting a kinetic model for the description of polycondensation of such monomers, the necessity arises to take account of the substitution effects whereas the polycondensation of the majority of monomers of the first type can be fairly described by the ideal kinetic model. The latter, due to its simplicity and experimental verification for many systems, is currently the most commonly accepted in macromolecular chemistry of polycondensation processes. 

All mathematical models require some assumed data on the source of release for a material. These assumptions form the input data which is then easily placed into a mathematical equation. The assumed data is usually the size or rate of mass released, wind direction, etc. They cannot possibly take into account all the variables that might exist at the time of the incident. Unfortunately most of the mathematical equations are also still based on empirical studies, laboratory results or in some cases TNT explosion equivalents. Therefore they still need considerable verification with tests simulations before they can be fully accepted as valid. 

Following risk assessment, the next step is to draft a formal validation plan. This is a written plan that includes all the specific validation procedures, installation tasks, acceptance testing, documentation requirements, reviews and verification tasks that need to be followed for proper system validation. The plan should also define individual responsibilities for these tasks and include an expected timeline. The plan should be designed around the URS and take into account the risk assessment determinations performed earlier. 

The TRAACS 800+ is controlled by a personal computer and the features provided include complete interactive control via keyboard or mouse calculation of results as necessary taking into account baseline or sensitivity drift, graphical output of calibration curves for all calibration types—either Hnear or non-hnear, input facility for sample identification data allowing storage on disc and real-time results together with chart traces on a computer printer. The programs allow easy access to input or data files and connection to other computers, and gives system performance verification to CLP standards and built-in QC charts. 

All equipment for which calibration is applicable must be periodically calibrated. Periodicity of calibration must take into account the type of the equipment, risk assessment, and previous results. An extremely short calibration periodicity becomes extremely expensive, whereas an extremely long calibration periodicity could result in poor verification results. Poor verification results mean that the results generated are wrong and therefore all results obtained since the previous calibration must be reviewed. In conclusion, adequate evaluation of the calibration periodicity is essential. 

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