Significance and Use
4.1 Equipment operability and long-term integrity are concerns that originate during the design and fabrication sequences. Such concerns can only be addressed or are most efficiently addressed during one or the other of these stages. Equipment operability and integrity can be compromised during handling and installation sequences. For this reason, the subject equipment should be handled and installed under closely controlled and supervised conditions.
4.2 This guide is intended as a supplement to other standards, and to federal and state regulations, codes, and criteria applicable to the design of equipment intended for this use.
4.3 This guide is intended to be generic and to apply to a wide range of equipment types and configurations.
4.4 The term equipment is used herein in a generic sense. See 3.2.6 for the definition.
4.5 This service imposes stringent requirements on the quality and the integrity of the equipment, as follows:
4.5.1 Leak tightness is required. This implies containment of liquids at all times, and retention of vapors and gases by means of vessel design, or through means of engineered provisions or operational procedures, or both, that ensure the retention, collection, and treatment of vapors and off-gases when the vessel cannot be fabricated or operated with an air-tight vessel configuration. Radioactive materials must be contained.
4.5.2 Equipment must be capable of withstanding rigorous chemical cleaning and decontamination procedures.
4.5.3 Equipment must be designed and fabricated to remain dimensionally stable throughout its life cycle.
4.5.4 Close fabrication tolerances are required to set nozzles and other datum points in known positions.
4.5.5 Fabrication materials must be resistant to radiation damage, or materials subject to such damage must be shielded or placed so as to be readily replaceable.
4.5.6 Smooth surface finishes are required. Irregularities that hide and retain radioactive particulates or other adherent contamination must be eliminated.
4.5.7 Equipment must be capable of being operated virtually unattended, unseen, and trouble-free over long periods.
4.6 It is assumed that the radiation hazards, combined with the need for confinement and containment, will necessitate a shielded enclosure cell equipped for some degree of remote handling and processing capability in the transuranic materials handling, processing, or machining operations (see 1.2.2).
4.7 Equipment intended for use in the processing and incorporation of radioactive wastes in host composites or matrices may operate at high temperatures and pressures and may require engineered provisions for the removal of large heat loads under normal and emergency conditions. The chemical corrosion and erosion conditions encountered in these processes tend to be extremely severe, placing emphasis on design for containment integrity.
4.8 Maintenance records from the plant or from a plant having a similar processing mission may be available for reference. If available and accessible, these records may offer valuable insight with regard to the causes, frequency, and type of failure experienced for the type and class of equipment being designed and engineered.
4.9 The constraints cited herein are intended to help the engineer establish conditions aimed toward the following:
4.9.1 Enhancing radioactive materials containment integrity,
4.9.2 Minimizing the loss of in-process materials or the spread of hazardous radioactive contaminants,
4.9.3 Minimizing equipment blemishes or faults that promote the adherence or retention of radiation sources,
4.9.4 Facilitating the ease and safety of decontamination and maintenance sequences, and
4.9.5 Reducing the failure frequency rate for all types and classes of equipment used in this service.
4.10 Exclusions:
4.10.1 In general, this guide is not intended to apply when the conditions set forth in 1.2.1 are irrelevant to the design of equipment or systems.
4.10.2 Given the conditioned exceptions set forth in 4.10.3, this guide is not intended to apply to the following:
4.10.2.1 Operations—Operation of equipment or facilities.
4.10.2.2 Uranium Ore Mining—Equipment or facilities associated with the mining of uranium ore.
4.10.2.3 Uranium/Plutonium/Heavy or Reactive Metals Processing Equipment—Equipment for the processing, machining and handling of uranium, plutonium, or other trans-uranic materials in metallic or other forms such as solutions, slurries, powders, or pellets when the radiation exposure levels are minimal, or when such operations are carried out in hoods or glove boxes and do not require massive radiation shield walls or enclosures. (See 1.2.2.)
4.10.2.4 Laboratory/Research and Development/Semiworks Equipment—Equipment for the above named facilities. The use of this guide in an unrestricted manner would result in equipment that is over-designed and costly for the above service conditions. (See qualification in 4.10.3.)
4.10.2.5 Ancillary and Support Services—Equipment and facilities designed for ancillary and service facilities that are located and installed outside shield walls, in spaces that are directly accessible for purposes of operation, maintenance and repair. (Note, however, the exception stated in 1.2.3.)
4.10.2.6 Nuclear (Fission) Reactors and Auxiliaries Thereof—Design of nuclear fission reactor vessels and auxiliary components and systems used in, or associated with, power reactor facilities or to nuclear reactors and auxiliaries intended for any other use or purpose. This guide does not apply to any equipment item or complex where the primary equipment design considerations include the dissipation of fission heat, or where the removal of radioactive decay heat loads resulting from reactor shutdown is a necessity, or both. (See qualification in 4.10.3.)
4.10.2.7 Decommissioning—Decommissioning of equipment. (See qualification in 4.10.3.)
4.10.2.8 Nuclear Criticality Safety—Design for nuclear criticality safety. (See qualification in 4.10.3.)
4.10.3 Given the foregoing non-applicability statement, this guide may be selectively applied to laboratory, research and development, and semi-works equipment when equipment integrity, materials containment, and the need for ease of cleaning are prime design considerations, where it is deemed essential to safety, or when it is otherwise justifiable. Also, many of the design criteria, guidelines, and caveats set forth herein will have applicability to certain equipment items and auxiliaries to be found in a reactor facility environment. Guidance provided herein relative to equipment features and provisions that minimize the retention of radioactive contamination in any form, and that facilitate cleanup and decontamination, will generally satisfy the potential need for equipment cleanup associated with the eventual decommissioning and disposal of the equipment. Specific guidance is provided in instances where design, fabrication, or integrity considerations are essential to the preservation of conditions or dimensions necessary to meet pre-determined and specified nuclear safety requirements.
Scope
1.1 Intent:
1.1.1 This guide covers equipment used in shielded cell or canyon facilities for the processing of nuclear and radioactive materials. It is the intent of this guide to set down the conditions and practices that have been found necessary to ensure against or to minimize the failures and outages of equipment used under the subject circumstances.
1.1.2 It is intended that this guide record the principles and caveats that experience has shown to be essential to the design, fabrication, and installation of equipment capable of meeting the stringent demands of operating, dependably and safely, in a nuclear processing environment that operators can neither see nor reach directly.
1.1.3 This guide sets forth generalized criteria and guidelines for the design, fabrication, and installation of equipment used in this service. This service includes the processing of radioactive wastes. Equipment is placed behind radiation shield walls and cannot be directly accessed by the operators or by maintenance personnel because of the radiation exposure hazards. In the type of shielded cell or canyon facility of interest to users of this guide, either the background radiation level remains high at all times or it is impractical to remove the process sources of radiation to facilitate in situ repairs or carry out maintenance procedures on equipment. The equipment is operated remotely, either with or without visual access to the equipment.
1.2 Applicability:
1.2.1 This guide is intended to be applicable to equipment used under one or more of the following conditions:
1.2.1.1 The materials handled or processed constitute a significant radiation hazard to man or to the environment.
1.2.1.2 The equipment will generally be used over a long-term life cycle (for example, in excess of two years), but equipment intended for use over a shorter life cycle is not excluded.
1.2.1.3 The material handled or processed must be retained, contained, and confined within known bounds for reasons of accountability or to minimize the spread of radioactive contamination.
1.2.1.4 The materials handled or processed must be kept and maintained within one or more of the following conditions:
(1) In a specific geometric array or configuration, and
(2) Within a range of conditions that have been determined to be a critically safe set of conditions for that piece of equipment, that is:
(a) In a given and specified operational position where adjacent nuclear criticality interaction conditions are known and unchanging,
(b) For a given and specified set or range of operating conditions, and
(c) For a given and specified process.
1.2.1.5 The equipment can neither be accessed directly for purposes of operation or maintenance, nor can the equipment be viewed directly, for example, without intervening shielded viewing windows, periscopes, or a television monitoring system.
1.2.2 This guide is intended to be applicable to the design of equipment for the processing of materials containing uranium and transuranium elements in any physical form under the following conditions:
1.2.2.1 Such materials constitute an unacceptable radiation hazard to the operators and maintenance personnel,
1.2.2.2 The need exists for the confinement of the in-process material, of dusts and particulates, or of vapors and gases arising or resulting from the handling and processing of such materials, and
1.2.2.3 Any of the conditions cited in 1.2.1 apply.
1.2.3 This guide is intended to apply to the design, fabrication, and installation of ancillary and support services equipment under the following conditions:
1.2.3.1 Such equipment is installed in shielded cell or canyon environments, or
1.2.3.2 Such equipment is an integral part of an in-cell processing equipment configuration, or an auxiliary component or system thereof, even though an equipment item or system may not directly hold or contain nuclear or radioactive materials under normal processing conditions.
Note 1: Upsets, accidents, or certain emergency conditions may be specified (and thus required) design considerations, but not necessarily acceptable or normal operating circumstances under this definition.
1.2.4 This guide is intended to apply to the design and fabrication of any and all types of equipment for radioactive wastes processing when any of the conditions cited in 1.2.1 apply. This would include equipment for waste concentration; for incorporation of wastes in selected host materials or matrices; and for the fixation, encapsulation, or canning of such wastes. It is intended to apply to all such wastes, regardless of the product waste composition or form. The product radioactive waste may have a glass, ceramic, metallic, concrete, bituminous, or other type of host material or matrices (composition), and may be in pelletized, solid, or granular form.
1.3 User Caveats:
1.3.1 This guide does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this guide to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.3.2 (Warning—This guide pertains to equipment used in and for the handling and processing of nuclear and radioactive materials. These operations are known to be hazardous for a variety of reasons, one being chemical toxicity.)
1.3.3 This guide is not a substitute for applied engineering skills. Its purpose is to provide guidance.
1.3.3.1 The guidance set forth in this guide relating to design of equipment is intended only to alert designers and engineers to those features, conditions, and procedures that have been found necessary or highly desirable to the acquisition of reliable equipment for the subject service conditions.
1.3.3.2 The guidance set forth results from discoveries of conditions, practices, features, or lack of features that were found to be sources of operational or maintenance trouble, or causes of failure.
1.3.4 It is often necessary to maintain the materials being processed within specific chemical composition or concentration ranges, or both. When such constraints apply, it may also be necessary to create and maintain a specific geometric array to minimize the chances of a nuclear criticality incident. Designers and engineers are referred to other standards for additional guidance when such requirements apply.
1.3.5 Equipment usage intent, service conditions, size and configuration, plus the configuration and features of the operating and maintenance environments have an influence on equipment design. Therefore, not all of the criteria, conditions, caveats, or features would be applicable to every equipment item.
1.3.6 It is intended that equipment designed, fabricated, procured, or obtained by transfer or adaptation and re-use of existing equipment, and installed in accordance with this guide meet or exceed statutory, regulatory, and safety requirements for that equipment under the applicable operating and service conditions.
1.3.7 This guide does not supersede federal or state regulations, or both, and codes applicable to equipment under any conditions.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
