Nuclear Criticality Safety

Criticality of U(3.85) Rods and Cylindrical Annuli In Water, . B. Johnson (UCC-ND) 

In recent years the Oak Ridge Critical Experiments Facility has reported data for large uranium-metal cylindrical annuli of 1.9 enrichment in U with water moderator and reflector. These studies have been extended to metal enriched to 3.85% in both as solid rods and as cylindrical annuli. 

The outside diameters of the iannuli were 7.2, 6.2, and 5.2 in., with inside diameters of 2.6 in. Solid rods slightly less than 2.6 in. in diameter cpuld be inserted into these annuli to produce effectively solid rods of each of the three outside diameters. All rods and annuli were 30 in. long. 

These rods and annuli were latticed in water in both square and triangular patterns, each at several spacings to determine the effect of moderation on criticality. The units in each lattice were arranged in the manner roost favorable for criticality so that the minimum number required was determined. The units in subcritical arrays were similarly arranged. Curves for each of the two patterns were obtained for each of the three diameter annuli and for each of the four diameter rods. In each case, the number of rods and the mass required for criti- 

I UNCERTAINTIES NOT THUS SHOWN ARE WITHIN THE LIMITS Of THE SYMBOLS. 

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Data from American National Standard for Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors [A2] and J. T. Thomas [Tl]. 

American Nuclear Society American National Standard, Nuclear Criticality Safety in the Storage of Fissile Materials, Report ANSI N16.5-1975, La Grange Park, 111. 

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. 

RESEARCH ON NUCLEAR CRITICALITY SAFETY AND ACCIDENT RISK EVALUATION FOR NUCLEAR FUEL CYCLE FACILITIES... 

Nuclear Criticality Safety and Accident Risk Evaluation for Nuclear Fuel Facilities 45... 

Reviews of designs from the point of view of their nuclear criticality safety, reviews of technical documentation of nuclear danger areas, plants, installation, and equipment if necessary, reviews of technical documentation for methods, tools, and the system of control over nuclear safety parameters final reports and conclusions based on the review results ... 

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. 

Ryazanov, B.G. (1996) Basic Principles and Nuclear Criticality Safety System in Facilities of Nuclear Industry of MINATOM, Russia, Russian-Chinese workshop on nuclear safety in spent nuclear fuel reprocessing, Beijing Nuclear Design Institute, Beijing, May 24-31. 

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. 

DOE 5480,24, NUCLEAR CRITICALITY SAFETY, which establishes nuclear criticality safety program requirements for Department of Energy (DOE) nuclear faci I ities,... 

AR518 3.71 Nuclear criticality safety standards for fuels and material facilities (ML003739492) (Draft... 

SNCSC Sandia Nuclear Criticality Safety Committee... 

The pertinent requirements for nuclear criticality safety at the HCF are described in SNL ES H Manual Supplement GN470072, Nuclear Criticality Safety (SNL 1998). This supplement addresses the requirements in all applicable DOE Orders, including the following ... 

Key guidance from the SNL ES H Manual Nuclear Criticality Safety Supplement (SNL, 1998) includes requirements to ... 

Operational controls, derived from a CSA [Mitchell and Romeo, 1999], are shown in Table 6.4-2. The referenced CSA addresses all aspects of HCF operations dealing with the chemical extraction/processing of isotopes from reactor-irradiated targets. The operational controls are implemented in accordance with the Nuclear Criticality Safety supplement to the SNL ES H Manual. 

Final responsibility for criticality safety at the HCF rests with line management. The Radiological and Criticality Safety Committee (RCSC) is chartered by the Nuclear Facility Safety Committee (NFSC) and members are appointed by the Deputy Director for Nuclear Facility Operations. The Sandia Nuclear Criticality Safety Committee (SNCSC), with... 

The RCSC provides independent reviews of criticality-safety issues and advises the HCF line management on criticality-safety matters. The RCSC reviews criticality-safety issues of proposed facility and equipment modifications, proposed experiments with fissile materials, nuclear criticality-safety limits, SNM storage procedures, and other aspects of nuclear criticality safety at the HCF. For criticality issues, the SNCSC oversees, reviews, and appraises the operation of the RCSC. The SNCSC is also available to provide additional review of criticality-safety issues when deemed appropriate, such as for issues involving a positive result from a USQD. 

Inventories of less than the threshold limits defined in the Applicability Section of the Criticality Safety Supplement to the SNL ES H Manual (which is consistent with ANSi/ANS-8.1) do not require criticality controls. However, if operations are planned to exceed those limits, appropriate nuclear criticality safety control are required. The following controls are applied to work at SNL geometry controls, criticality index (Cl) control, administrative controls, mass controls, and other nuclear crifa cality safety controls (density controls, neutron absorbers, and moderation controls). Preference of the control method depends upon whether the operation is temporary (e.g., an experiment) or permanent (e.g., a long-term storage facility). The first... 

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

Safety-analysis capabilities are contained within the Nuclear Facility Operations and Nuclear Technology Programs organizations. These organizations produce Safety Analysis Reports for both reactor and nonreactor nuclear facilities, primarily in TA-V. Other organizations provide specialized safety-analysis support in the form of mechanistic accident-progression analysis, heat transfer, structural analysis, neutron transport, nuclear criticality safety, and other areas upon request. 

EWING, R.I., Bumup verification measurements at US nuclear utilities using the Fork system , Nuclear Criticality Safety (ICNC 95, Proc. 5th Int. Conf. Albuquerque), Vol. 2, Univ. of New Mexico, Albuquerque, NM (1995) 11.64—70. 

MENNERDAHL, D., Mixing of package designs Nuclear criticality safety . Packaging and Transportation of Radioactive Materials, PATRAM 86 (Proc. Symp. Davos, 1986), IAEA, Vienna (1986). 

The Nuclear Criticality Safety Guide, Rep. LA-12808, Los Alamos National Laboratory, Los Alamos, NM (1996). 

Any drop test should be conducted with the contents of the package simulated to its maximum weight. More than one drop may be necessary to evaluate all possible drop attitudes. It may also be necessary to test specific features of the package such as hinges or locks to ensure that containment, shielding and nuclear criticality safety are maintained. 

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

The achievement of proper operating conditions, prevention of incidents, or mitigation of incident consequences, resulting in protection of workers, the public, and the environment from nndne radiation hazards. This covers nuclear power plants as well as all other nuclear facilities, the transportation of nuclear materials, and the use and storage of nnclear materials for medical, power, industry, and military uses. In addition, there are safety issues involved in products created with radioactive materials. The Office of Nuclear and Facility Safety establishes and maintains the Department of Energy (DOE) reqnirements for nuclear criticality safety. The DOE s detailed requirements for criticality safety are contained in Section 4.3 of the DOE Order 420.1, Facility Safety. Criticality safety requirements are based on the documented safety analysis leqnired by 10 CFR 830, Subpart B. 

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