International Criticality Safety

The first task, the selection of appropriafe benchmark experiments, is greatly aided by the International Criticality Safety Benchmark Evaluation Project (ICSBEP). This project is managed through Idaho National Laboratory (INL) and involves nationally known criticality safety experts from various national laboratories in the United States. 

Source ICSBEP International Critically Safety Benchmark Evaluation Project (http //icsbep.inel.gov/) (Accessed date 7/26/2014). 

M. C. Brady and T. L. Sanders, A Validated Methodology for Evaluating Bumup Credit in Spent Fuel Casks, Proceedings of International Conference on Nuclear Criticality Safety, Christ Church, Oxford, United Kingdom, September 9-13, 1991. 

Since 1995, work on documenting and estimating the results of critical experiments has been carried out in the IPPE facility with the aim of including them in the International Handbook of Evaluated Criticality Safety Benchmark Experiments [3]. Currently, the following critical experiments have been included in the Handbook ... 

In order to determine how reliable the nuclear criticality safety measures are for installations, plants, institutions, and the nuclear complex in general, the NSD, IPPE, developed a special database, that uses a technique for determining indices of any danger of failure and corresponding software to determine the frequency of nuclear accidents. The technique has been verified by means of the database on nuclear accidents that have happened in the past at nuclear industrial enterprises. The results of nuclear accident frequency estimation were presented in a paper submitted to the international conference on nuclear criticality safety in Albuquerque [9]. The technique is universal and can be used to estimate the frequency of any accident (e.g., nuclear, radioactive, technological). In order to get the results. 

Gurin, V., Sviridov, V., Ryazanov, B. (1995) Survey of Integral Nuclear Criticality Safety Experiments Performed at SSC RF IPPE. Proceedings of the Fifth International Conference on Nuclear Criticality Safety, Albuquerque, New Mexico, U.S., September 17-21, pp. 4.48-4.54. 

International Handbook of Evaluated Criticality Safety Benchmark Experiments, NEA/NSC/DOC (95) 03, September 1997 Edition. 

G. W. Mitchell and D. J. Romero, 1999, Hot Cell Facility Criticality Safety Assessment for Storage of Medical Isotope Targets and Process Waste, a draft Internal Memorandum Report, Sandia National Laboratories, Albuquerque, NM, March 1999. 

Sandia National Laboratories (SNL), 1998, Nuclear Criticality Safety, ES H Manual, Supplement GN470072, Sandia National Laboratories, Albuquerque, NM, January 28, 1998 (SNL Internal Web). 

Eusgeld I. Kroger, W. 2008. Comparative Evaluation of Modeling and Simulation Technique for Interdependent Critical Infrastructures Proc. of the Ninth International Probabilistic Safety Assessment Conference, Hong Kong, Mai 18-23, 2008,49-57... 

Vn.9] INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, Nuclear Energy — Fissile Materials — Principles of Criticality Safety in Storing, Handling, and Processing, ISO-1709, ISO, Geneva (1995). 

VII.20] The 1991 International Conference on Nuclear Criticality Safety (ICNC 91) (Proc. Conf. Oxford, 1991), 3 Vols, Oxford, UK (1991). 

Certain critical safety functions require systems more reliable than a DCS, and they must be handled separately. These functions are associated, for example, with rectifiers, hydrogen compressors, and brine purging of membrane cells. In the past, redundant programmable logic controllers (PLCs) often provided the necessary reliability, but newer systems with the robustness of a standard PLC also have internal redundant logic and input checking and may also have redundant outputs. 

In -the moderation-control method for S% enriched UFii, criticality safety is assured by control of two parameters- the U enrichment and the hydrogen moderation. Topical subjects to be reviewed in method development include UF , purity control in liquefaction operations the Influence of container size on internal and external moderntion effects decoupling properties of the cylinder wall In water-moderated UFa arrays special neutron multiplication experiments with large UFo assemblies derivation of moderation control limits large cylinder cleaning procedures and protective packaging. The administrative requirements for method application are al.so discussed briefly. 

Increased concern over the potential diversion of nuclear materials has led to an escalation in materials safeguards requirements nationally and internationally. As with any externally imposed regulations, these may be expected to impact operations and nuclear safety. This paper identifies m or concerns as they relate to tte conduct of nuclear criticality safety. 

A weapons country like the United States will implement international safeguards only as a diplonutic expedient to encourage other nations to accept IAEA inspedion. Although not yet in effect here, the safeguards may be expected to affect criticality safety mainly through process changes which may be required to assure that inventories can be verified independently by IAEA personnel. The presence of an on-site inspector and the use of containment and surveillance methods will also perturb the overall operations. 

Criticality Safety of an Annular Tank for Fissile Solution, Robert E. Rothe (Rockwell International)... 

Resolution of Safety Issues Identified by DOE Internal Oversight 1997-2 Continuation of Criticality Safety... 

The work of the ICSBEP is documented as the International Handbook of Evaluated Criticality Safety Benchmark Experiments, which is distributed by INL as a set of annually updated CD or DVDs. The handbook currently contains 464 evaluations covering more than 4000 critical, near-critical, or subcritical configurations. Table 21.6 gives an overview of the experiments available from the database. 

FIGURE 2.8 The decrease in content in fuel (a) and buildup of (b) as a function of the burn up. (From Kovbasenko, P. et al., Comparative analysis of isotope composition of VVER-1000 spent fuel depending on their manufactory and operation conditions, in Seventh International Conference on Nuclear Criticality Safety, ICNC, Tokai-Mura, Japan, 2003, p. 13. With permission.)... 

FIGURE 2.9 Separation on Sm and Nd in irradiated mixed oxide sample after injection of 1 mL containing 20 pg fuel mL- measured with the HPLC-Quadrupole ICPMS system. (From Gunther-Leopold, I. et al.. Characterization of spent nuclear fuel by an online combination of chromatographic and mass spectrometric techniques, in Proceedings of the Seventh International Conference on Nuclear Criticality Safety, ICNC, Tokai, Japan, October 2003, JAERI-Conf 2003-019, 2003. With permission.)... 

To gain the necessary knowledge themselves the safety specialists participate in external trainings (in the USA and Great Britain) and safety conferences and are members of relevant societies (e.g. the International System Safety Society and the Safety-Critical Systems Club) as there are not many possibilities for a complete safety education in central Europe yet. An additional goal of these activities is the early recognition of new or revised legal requirements. 

However, the international nuclear safety organizations such as IAEA and WANO are themselves not immune to some criticism. Had they pointed out forcefully to both TEPCO and the J apanese nuclear safety regulator NIS A that US nuclear plants similar to Fnknshima Daiichi had had significant safety upgrades carried out, and TEPCO shonld do likewise If not, why not )... 

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