Criticality Procedures for

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Released through the Record Copy held at Mound Facility CRITICALITY PROCEDURES FOR SW BUILDING DEVICES GROUP AREA The following procedures will be used by the Devices Group in addition to those set forth in MD-10038, Nuclear Criticality The Research Department's Devices Group SW Building areas pletely occupied by Devices Group, while the responsibility for SW-1B is shared by Devices Group and the Y Item Component Presently the Production Group in SW-1B does not foresee any use of fissionable material in SW-1B; consequently, only the operations of the Devices Group will be considered. 2. Materials and Mass Limits Fissionable materials that could be present in the Devices SW

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Plutonium-239. The criticality unit values for these materials are defined in MD-10038 (Ch. 3) Nuclear Criticality Precautions by the Mound criticality committee. There shall be a limit of one criticality unit of fissionable material present in any the sum of the percentages of a criticality unit of each fissionable material present shall not exceed one hundred per cent. These Unit Value for For Metal Sphere Aqueous Soln. 2.2 Material Limits for Dry-Box Lines Since a criticality unit has been established as a mass limit for a single room, a complex limiting system is omitted for individual box lines, other than that a maximum of 300 grams of fissionable scrap may accumulate in any one operating line. An entry and exit log must be maintained which accounts in detail for the presence of fissionable material in each box

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Wh.n a maximum of 300 grams of unrecovered fissionable scrap has accumulated operations must cease in the line and the line will be completely cleaned. Cleaning requires removal of all scrap in the line and scrubbing of the line including all equipment remaining in the box line. Scrub liquids will be handled as scrap solutions or slurries with the limits given in paragraph 2. 3.1 There are no restrictions on the number of birdcages in SW-142, SW-1B or SW-9, so long as the single Criticality Unit limit is observed. Birdcages will be available and used for transportation and temporary storage of material whenever fissionable material in the room is not in a box line. Any filled birdcages not needed in the area will be properly stored in the T-Building Criticality Vault. Filled birdcages will be sealed with a lead or other tamper seal when stored or transported out 3.2 No birdcage shall contain over one Criticality Unit unless the procedures on section 4 are followed.

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4. Exceptions to Criticality Limits Occasionally, there is some necessity for transfer of items containing amounts of fissionable material greater than one criticality unit into the Devices SW Area. These items may be for fabrication and assembly, may be temporarily held for surveillance or may be dismantled. For single devices containing greater than one criticality unit but less than 2.3 criticality units, assembly, disassembly or testing is permitted so long as other fissionable materials are not in the room. If a single device contains gteater than 2.3 criticality units of fissionable material, specific approval from the Criticality Committee will be required before movement of the item into the area. The request for committee approval will detail all handling procedures. The separate box lines in SW-142 may be described by their functions, i.e., Reaction and Pressing, Machine, Metallographic The metallographic Line is used for processing metallographic samples from material used in devices. Weighed samples from

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rejected or developmental parts which have been sectioned or disassembled are moved to the metallographic line where they are ground, polished, and etched for examination. Polished specimens are re-weighed upon removal for examination which will normally be conducted in SW-142. Occasional specimens of 25 grams or less may be moved to R-173 for examination. Solutions, scrap and slurries of material formed in these operations are accumulated in reservoirs for periodic removal. A log is attached to the box line which notes all entries and exits of fissionable materials, as well as yet unrecovered material remaining in the line. The scrap removal procedures as set forth in section "Material Limits 5.1.2 Reaction and Pressing The reaction and pressing line is used for synthesizing materials and pressing components for the devices assembled in the assembly boxes. No fissionable material is permitted in this line because of the difficulties introduced by cross-contamination. 5.1.3.1 Machine and Assembly Fissionable material in various enrichments is sometimes used for fabrication of device sub-assemblies in SW-142. These materials are normally handled in the Machine Box Line and the Assembly Box Lino. Occasional assembly where no welding or machining is

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required is performed in fume hoods which provide entrance to this or the Metallographic Line. 5.1.3.2 Shaped parts from other sites are received for processing and assembly into devices. Assembly is performed in the Assembly Line except as noted in paragraph 5.1.3.1. The parts are welded in the assembly line and the sub-assemblies reshaped by machining or polishing in the Machine Line. Dismantling of the devices is also performed in the Machine Line, where parts may be disassembled by sawing, turning, or milling. 5.1.3.3 When any machining is done on a part, all scrap is carefully collected and weighed, and a detailed account of these weights kept in the log book attached to the box line. The scrap is collected and stored in a birdcage until shipped out as scrap. 5.1.3.4 A maximum of 300 grams of unrecovered scrap may be allowed to accumulate before operations must cease in the line and the line is completely and thoroughly cleaned. 5.1.4 A part may be leak-tested using an ionization chamber as long as 24 to 48 hours, depending upon the assembly stage. These

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chambers are in SW-1B and SW-142 and are not in the lines or birdcaged. Devices must be under strict administrative control during this check. 5.2 Work performed outside the SW-142 devices area on devices or parts containing fissionable material, includes: 5.2.1 X-ray inspection is done in either T-212 or T-5, where the item is removed from the birdcage in which it was transported. The part is placed on a cassette and x-rayed, then returned to the birdcage for return to SW-142. 5.2.2 Gamma spectroscopy is performed in either R-115 or R-116, where the part remains in its birdcage during analysis. 5.2.3 Calorimetry is done in SW-13, R-111 or R-108. The item is removed from its birdcage, placed in a calorimeter can in the calorimeter for measurement. It is then replaced in the birdcage. 5.2.4 The parts may be gauged in DS-103, where they are removed from their birdcage, gauged, and replaced in the birdcage. 5.2.5 The items will be stored in birdcages in the T Building Criticality Vault. Solutions, scrap and slurries of material formed in these operations are accumulated in reservoirs for periodic

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removal. A log is attached to the box line which notes all entries and exits of fissionable materials, as well as yet unrecovered material remaining in the line. The scrap removal procedure as set forth in 2.2 will be used. During all the above operations the criticality limits for fissionable materials will be observed in all areas where the work takes place. The Component Production Group plan to have natural uranium in SW-1B in small amounts which will be insufficient to precipitate any problem. The Devices Group will use SW-1B only for temporary. holding of material in birdcages for use in SW-142 or SW-9 and calorimetry. Occasional leak checking may be done and this will be performed using an ionization chamber as in earlier text. The work involving fissionable material in SW-9 includes the assembling, welding and reshaping of exterior shells of subassemblies containing fissionable material and the temporary storage of birdcaged items or scrap. 5.4.1 The procedures set forth for the operations of the Machine Line in SW-142 will also apply here concerning mass limits, transfer, scrap collection and material accountability.

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5.4.2 Temporary storage of birdcages necessitates keeping a strict log of all material entering and exiting the machine hood and the room itself, always adhering to the limits of these 6.1 All fissionable materials held in SW-142, SW-1B or SW-9 will be kept in the operating lines while being processed or will be kept in birdcages. Exceptions occur during gauging or leak testing and occasional assembly procedures. 6.2 When fissionable material is being stored or processed in SW-142, SW-1B or SW-9 a minimum of two usable birdcages will be kept available for their storage. 6.3 All fissionable materials moved inside or outside the Devices Area will be contained in birdcages which will be transported on approved hand trucks. 6.4 All parts will be weighed before placing them in a box line, and after machining or reworking, will be re-weighed upon removal from the line. 6.5 A detailed log book accounting for all fissionable materials entering and exiting a line will be kept for each line. The log

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will show what material inside the box line is yet unrecovered in the form of scrap. 6.6 All criticality limits mentioned in Sections 2 and 4 must be applied to all work in the Devices SW Building Area. 6.7 The area supervisor will be informed and approve of the movement of any fissionable material in the area which exceed 1/10 7.1 The Criticality Committee has classified the Devices SW Area 7.2 Water cannot be used in any of the areas due to the danger of reaction with the various lithium hydrides present, which could cause fire and explosion. 7.3 There are no installed fire control systems in these areas; portable equipment will be used. Carbon dioxide and dry chemical eutectic salts equipment are the only acceptable and permissible extinguishers for the Devices SW Areas. Other methods can be used only with permission of the operating personnel. 7.4 Control of fire is aided by handling of combustible materials in inert gas atmospheres, prevention of large scrap accumulations, and the presence of CO2 and eutectic salts fire extinguishers.

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8.1 A specified exit route from the area is shown for criticality emergency evacuation. The closest exterior exit is the security door at the north end of SW Building, which opens into the north corridor. Personnel in SW-9, SW-1B and SW-142 will all use this The pre-assigned assembly area for an evacuation for SW Building is the plant garage.