[en] The results of a physical inventory at a reference bulk materials handling facility (described in the appendix) are evaluated and the materials balance and the material unaccounted for (MUF) obtained. The uncertainty associated with MUF and its importance are explained. The procedures needed to determine whether the MUF indicates a real loss of greater than a given magnitude has occurred, or whether it is more reasonable to conclude that no loss has occurred, are described. 5 refs., 3 figs., 10 tabs

[en] Using a simple analysis of the balance equation for the accounting for, and control of nuclear material, principles and procedures of safeguards are explained. (author)

[en] For a number of years the Statistical Analysis Section (PSA) of the Concepts and Planning Division of the IAEA Department of Safeguards has participated in the State evaluation activities preliminary to the implementation of integrated safeguards, as well as in the assessment of verification results in States where integrated safeguards measures have been implemented, through the analysis of State declarations and measurement data collected by inspectors. Two types of analyses are performed: quantitative analyses supporting the verification of the correctness of States' declarations, and qualitative analyses that contribute to conclusions about their completeness. In the traditional context, material balance analyses rest on stratified balances of nuclear material, taking into account the increases and decreases declared for each material type during a material balance period and the uncertainties associated with these inventory changes. By integrating material balance evaluation and environmental sampling results in the context of special investigations, PSA is now performing flow assessments of the chronological balance of nuclear material along the various stages of its chemical and physical transformation within and across material balance areas in a State. The term 'integrating' in this context refers to bringing together information from different sources in order to draw a conclusion about the possibility of nuclear material diversion or proliferation-related activities. The proposed concept does not affect the intrinsic principles of the independent analyses leading to environmental sampling and material balance evaluation results, but rather broadens the scope of traditional material balance studies by bringing together material balance and environmental sampling conclusions at the different stages of an investigation. The concept of integrated material balance evaluation is illustrated in this paper through hypothetical examples. (author)

[en] The system is subdivided into three complexes: conventional fission product bookkeeping with quantity checks on incoming and outgoing material at a few key measuring points as well as inventory on the occasion of the annual closedown for operational reasons; determination of inventory and balancing with the plant in operation via the measuring data of in-process instrumentation of vessels and apparatures in fule reprocessing or tracing of fission products in mixed oxide manufacture by charges down to the production of fuel elements, respectively; control checks at crucial monitoring points by measures of spatial limitation (containment) and observation (surveillance) to be determined by means of analyses of relevant diversion pathways carried out systematically. (orig./HP)

[en] Traditional materials accounting is focused exclusively on the material balance area (MBA), and involves periodically closing a material balance based on accountability measurements conducted during a physical inventory. In contrast, the physical inventory for Los Alamos National Laboratory's near-real-time accounting system is established around processes and looks more like an item inventory. That is, the intent is not to measure material for accounting purposes, since materials have already been measured in the normal course of daily operations. A given unit process operates many times over the course of a material balance period. The product of a given unit process may move for processing within another unit process in the same MBA or may be transferred out of the MBA. Since few materials are unmeasured the physical inventory for a near-real-time process area looks more like an item inventory. Thus, the intent of the physical inventory is to locate the materials on the books and verify information about the materials contained in the books. Closing a materials balance for such an area is a matter of summing all the individual mass balances for the batches processed by all unit processes in the MBA. Additionally, performance parameters are established to measure the program's effectiveness. Program effectiveness for verifying the presence of nuclear material is required to be equal to or greater than a prescribed performance level, process measurements must be within established precision and accuracy values, physical inventory results meet or exceed performance requirements, and inventory differences are less than a target/goal quantity. This approach exceeds DOE established accounting and physical inventory program requirements. Hence, LANL is committed to this approach and to seeking opportunities for further improvement through integrated technologies. This paper will provide a detailed description of this evaluation process.

[en] The purpose of this document is to provide a detailed description of a system for the accounting for and control of nuclear material in a research laboratory facility which can be used by a facility operator to establish his own system to comply with a national system for nuclear material accounting and control and to facilitate application of IAEA safeguards. The scope of this document is limited to descriptions of the following SSAC elements: (1) Nuclear Material Measurements; (2) Measurement Quality; (3) Records and Reports; (4) Physical Inventory Taking; (5) Material Balance Closing

[en] The authors consider possible ways of applying probability methods to solve problems involved in accounting for nuclear materials. The increase in the flow of nuclear materials subject to IAEA safeguards makes it necessary to increase the accuracy of determination of the actual quantities of nuclear materials at all stages of their processing and use. It is proposed that the IAEA's automated system of accounting for nuclear materials, based on accounting information for each material balance zone and the results of random experimental checks performed by IAEA inspectors, be supplemented with mathematical models of the flow of nuclear materials in each balance zone based on the data supplied for each facility in the balance zone when it was placed under safeguards. The statistical error in determining the material balance and the material unaccounted for can be considerably reduced in this way even if the experimental control methods are retained. (author)

[en] This paper describes a safeguards approach that can be deployed at any modern plutonium processing facility to increase the level of safeguards assurance and significantly reduce the impact of safeguards on process operations. One of the most perplexing problems facing the designers of plutonium processing facilities is the constraint placed upon the limit of error of the inventory difference (LEID). The current DOE manual constrains the LEID for Category I and II material balance areas to 2 per cent of active inventory up to a Category II quantity of the material being processed. For 239Pu a Category II quantity is two kilograms. Due to the large material throughput anticipated for some of the modern plutonium facilities, the required LEID cannot be achieved reliably during a nominal two month inventory period, even by using state-of-the-science non-destructive assay (NDA) methods. The most cost-effective and least disruptive solution appears to be increasing the frequency of material balance closure and thus reducing the throughput being measured during each inventory period. Current inventory accounting practices and systems can already provide the book inventory values at any point in time. However, closing the material balance with measured values has typically required the process to be cleaned out, and in-process materials packaged and measured. This process requires one to two weeks of facility down time every two months for each inventory, thus significantly reducing productivity. To provide a solution to this problem, a non-traditional approach is proposed that will include using in-line instruments to provide measurement of the process materials on a near real-time basis. A new software component will be developed that will operate with the standard LANMAS application to provide the running material balance reconciliation, including the calculation of the inventory difference and variance propagation. The combined measurement system and software implementation will make it possible for a facility to close material balances on a measured basis in a time period as short as one day

[en] The term fuel cycle oriented approach is currently used to designate two quite different things: the attempt to consider all or part of a national fuel cycle as one material balance area (MBA) or to consider individual MBAs existing in a state while designing a unique safeguards approach for each and applying the principle of nondiscrimination to fuel cycles as a whole, rather than to individual facilities. The merits of such an approach are acceptability by the industry and comparison with the contemplated establishment of long-term criteria. The following points concern the acceptability by the industry: (1) The main interest of the industry is to keep an open international market and therefore, to have effective and efficient safeguards. (2) The main concerns of the industry regarding international safeguards are economic burden, intrusiveness, and discrimination. Answers to these legitimate concerns, which retain the benefits of a fuel cycle oriented approach, are needed. More specifically, the problem of reimbursing the operator the costs that he has incurred for the safeguards must be considered

[en] The new approach for the application of materials accountancy, called ''near-real-time materials accountancy'', is described and the practical feasibility as well as the possible improvements are discussed in comparison to the conventional approach. In the case of a reference reprocessing facility with an annual throughput of 1000 t heavy material the application of this procedure is simulated and the resulting improvement in detection sensitivity demonstrated. (author)