ML19221B328

Reg Guide 5.42 Design Considerations for Minimizing Residual Holdup of Special Nuclear Matl in Equipment for Dry Process Operations

ML19221B328
Person / Time
Issue date:	01/31/1975
From:	NRC OFFICE OF STANDARDS DEVELOPMENT
To:
References
REGGD-05.042, REGGD-5.042, NUDOCS 7907200038
Download: ML19221B328 (7)

Text

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g aGY (

U.S. ATOMIC ENERGY COMMISSION (g M g REGULATORY GUDDE

%,4 re s o' DIRECTORATE OF REGULAMRY STANDARDS REGULATORY GUIDE 5.42 DESIGN CONSIDERATIONS FOR MINIMlZING RESIDUAL HOLDUP OF SPECIAL NUCLEAR MATERIAL IN EQU PMENT FOR DRY PROCESS OPERATIONS A. INTRODUCTION dry proce 9 : rations.1 The design features noted will facihtate physical mventory measurements and reduce Paragraph (b) of Section 70.22, "Centents of Apph.

matenal balance uncertainties. They are not expected to cations," of 10 CFR Part 70,"Special Nuclear Matenal,'

mterfere excessively with process operations in parucu-requires, among other things, that each appbcation for a lar, this guide is appbcable to(l) gas handling,(2) glove.

hcease to possess at any one time more than one box operations, (3) calcining, (4) dry sobds transfer, effective kilogram of spec a. nuclear material (SNM)

(5) dry blendmg and classi9 cation, (6) packed bed con.

contain a full desenption of the appbcant's program or versions, ud (7) commin ution.

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control of and accountmg for SNM that will be in his possession under hcense, mcludmg procedures for con-B. DISCUSSION trolhng SNM during its processing or use in the facihty and procedures by which process losses are determined I. Background 70.51. "M.;tenal Balance, Inven tory, and 9

Section Records Requirements," indicates that certain licensees Past expenence and current observation of pr ess must co iduct their nuclear matenal physical mventones operations used in various systems indicate that the in compliance with specific requirements.

publication of general guidelines for equipment design The control of and accountmg for SNM can be made could assist in achieving the degree of material control more effective by reducmg residual holdup m process and accountmg needed for satisfactory protection cf equipment following dramdown and cleanout. Such a SNM Suable amounts of SNM accumulate as deposits reduction would lesv me seventy of the problems dunng matenal processmg or draindown For certam associated with determming the residual holdup com-process steps, modes of operation, and types of matenal, ponent of a physical inventory and would reduce the the quantity of the accumulated deposit may reach a uncertamty component contributed by residual holdup.

steady state that Ductuates around some charactenstic The purpose of this guide is to call the attantion of ar..ount. In other instances, a deposit may continue to individuals who participate m equipment design and accumulate as the process continues to operate and may layout and in measurement control to the u+ility and not become apparent until draindown or cleanout. In significance of reducmg residual holdup. This guide, either case, the quantity of SNM tn residual holdup Se re fore, is intended for plant managers, designers, fouowing dramdowr often is difficult to determme with opeators, material control personnel, and others at the sufficient precision and accuracy to meet mate nal dension-making level who mclude safeguards as an 4

C mtegral part of their professional activities.

I Regulator > Guide 58 addresses drpng and fluidues txd o

Tlus guide desenbes design features acceptable to the Regulatory staff for mtmmumg the residual hohtup of.

operations for purposes of nununmng reudual holdup of SNM Regulatory Guide 5.25 addresses reudual holdup proMerns h

SNM after dramdown or cleanout of equipment used m uruque to equipment used for wet process operations.

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unaccounted for (MUF) and bm2ts of error of MUF

b. Glovebox Operatwns (LEMUF) requirements. Appropnate desipi could m-crease the effectiveness of draindown and assist tn Gloveboxes are used pnncipally for handling reducing residual hoidup and the consequent need for matenals containing uraniam 233 or plutonium.

determming the retamed SNM. Good design also should improve the capab:hty for any needed cleanout follow-mg draindown.

c. Calcining Mminuzing the quantity of matenal retamed m equipment atter draindown generally enhances the effec.

Calcimng is applied to dned sohds that have been tiveness of a matenal protecuon program in the follow.

produced m a precipnation step. For example, plu-ing ways:

tomum oxalate is calemed to plutomum oxide. The oxide product from the calciner may be subjected to commmution and/or blendmg before it becomes feed for

a. Quality of Physicallnsentories the fabrication of fuel. Some equipment can be used to perform both drying and calcimng simultaneously. Cer-Reduemg the quantity of residual holdup that is tam ty pes of scrap or waste may be calcined is part of not amenable to measurement improves the quahty of a the recyhng or recovery ofits contained SNM physical inventory.2 The extent to which the measure-ment of the residual holdup contributes to the quality of

d. Dry Solids Transfer a physical inventory depends on the amount of holdup and the uncertainty of the measurement method.

Dry soh..us are transferred in a number of fuel conversion or fabncation steps. For example, dry am-

b. Susceptibility and Accessibility of SNM monium diuranate (ADU) powder formed dunng the drymg of the filter cake from an ADU precipitation if the quantity of residual holdup remaining after process is transferred to a calcinmg fumace for conver.

draindown and/or cleanout of equipment i; reduced,less sion to uramum dioxide. Similarly, dned mixed SNM is accessible and susceptible to theft or diversion plutonium-uramum oxides formed by copreupitation dunng the samphng, identification, and evaluation neces-are transferred to the next process step. SNM oxid-sary to complete a physical inventory. bssening the powders are transferred to blenders and to fuel pelletiz.

effort necessary to remove and/or evaluate residual ing equipment.

holdup reduces the arnount of time SNM is accessible, the number of people who need access to it, and the opportunity for unauthorized individuals to ga2n access

e. Dry Blending and Particle Classification to SNM dunng a physicalinventory.

Blendtng and classifymg are commonly utilized m vanous chemical conversion and fuel fabncation pro.

2. Unit Operations cesses. Examples include the ammoruum diuranats or fluid-bed processes for uranium conversion; the con.

This guide deals with the reduction of residual SNM venion of mtxed uranium-plutonium nitrates to mixed holdup during a physical inventory m seven process uranium-plutoruum oxides; and the fabncation of sphen-operatir as common to dry chemical processmg. These cal particles by spheroidizing and particle coatmg.

operations are desenbed in the followmg paragraphs.

Dry particu! ate matenals may be ble.1ded to pioduce a umform mixture of two or more matenals havmg different chenucal compositions, particle sues,

a. Gas Handling shapes, surface areas, or other properties.

Classification can be used to produce a controlled Gas handhng operations considered here melude particle sin distnbution or shape for matenals to be handbng of (1) process gases and C) carner gases that blended or for matenals that beve been blended just may contam suspended SNM p articlet The transfer of pnor to fabr ce: ion.

UF fmm shipping contamers to process sessels is the Blendmg and classifymg may be performed as 6

most common example of the handhng of gaseous SNM separate or combmed operations.

in a fuel conversion facility. Offgases from activities scch as drying, calctncuon, pneumatic sohds transfer, and

f. Pached Bed Chemical Conversions fluidized bed reactwns contam SNM m particulate form, the use of filters, cyclones, and sc ubbers to remove these particulates from the gas streams should b, Packed bed c inversions can be ned for converimg a whd uran um corroound to a metal or to another sohd considered, coinpound by a contrclled exothennic batch reduction process. For example, this type of operation is used for the reduction of urarium tetraduor.de to uranium metal 2 Regula tor y Guije 5.13 adireues tse subject of condutmg physwal tmentones of nuclear materul.

with magnesium or calcium metal. Campounds of other 5.42-2

metals may be added to effect a coreductior that yielos c'uctwork and filters. Matenal can also be inadvertently an aUoy product. Packed bed operations may also be spilled mto maccessible locations mthm the calemer used foi the reactwn of uraruum dioxide with carbon or dunng operauon. The fact that the calemed powder graphite to produce uranium carbides.

usually has a high Fulk den;ity helps to reduce dustmg m handhnt

g. Comminution Direct heaung m calemers usmg a heated gas stream can cause dast particles to became entramed in the gas apphed to dned or calcined stream. Indirect heating and direct radiant heating, on Con mmuuon is oxides in 3rder to obtam a powder suitable for fabnca.

the other hand, do not normally contnt;ute to holdup.

tion mto dared fuel shapes. It also may be appbed to Cylindncal rotatmg-retort calciners are particularly dned caxe or a sobd scrap (which is bemg prepared for desirable for high. throughput, low-holdup operation.

recychag) from i fat ncation process.

These calemers, which may be operated continuously, The prodtAt of commmurion is a fine, free-Gowmg have the advantares of mintrnum phy.N handhng of powder with a fairly uniform particle sue distnbuuon.

product z,d great potential for automat;oa. However, The commmution equipment is select.d so as to control the pesence of hitmg bars or Hight carnages m these particle size and surface area of the powder and to calemers makes them more difficult to drain down or obtain the desired pelletinng and smtenng properties.

clean out fer a physical mventory of SNM.

Ball nulls or rod nulls may be used to combine A batch or semicontinuous operation with trays of blendmg with a comminution step.

material trave ing through an indirectly heated mufne-l type calciner has comparatively little holdup, unkss the

3. Holdap in Gas Handling trays are accidentally tipped and the contents sedled into the calciner as a result of mechanical malfunction of The holdup problems m equipm-t for handbng gases he tray conseyer systems. This problem can be greatly fallinto the following two general categones:

reduced by the use of cosered trays.

a. These problems related to the storage and transfer

6. Holdup in Dry Solids Transfer of UF, includmg the prevention of condensation of 6

UF in transfer 1mes by heating, the re. ioval of as much Dry pawders usually are moved from one process step 6

gas as possible from the contamers by heatmg and to another by manual, mechanical, or pneumatic means.

purgmg and ;he accurate measurement of the residual The manual method mvolves loadmg a containct at the

" heel" m the container.

discharge pomt of equipment for one unit process and movmg it by hand to the charging position of the

b. Those problems related to SNM particulates en-equipment of the next unit process. T1us technique is trained m g'.seous wute streams, including the deposi.

generally employed when relatively small quanuties of tion and accumulation of particul-tes in ducts, filters, matenal are involved. When properly designed, the cyclones, and scrubbers.

containers used to manually transfer dry solids can be cleanly emptied except for the small amount of matenal

4. Hddup in Gloveboxes that chngs to the inner surface. Tlus residual matenal can easdy be removed by brushing, vacuuming, or Holdup problems in gloveboxes are related to the dissolution.

type of operauons and to the degree ofleak tightness of Mechanical conveyors have broad application in the the process eqwpment mstalled within the glovebox.

chemicalindustry, but are not generally used for transfer Eauipment that 's totally and rehably enclosed and is of matenal containing SNM. Scraw and belt conveyors essenually automatic in normal operation contnbutes have been used in some operations for movmg large negligible holdup to gloveboxes. Problems of holdup auanuues of ADU powders. Holdup problems with anse dudng mamtenance or other nonroutme operaung mechanical conveyors generally anse as a result of penods when process containments are breached.

matenal adhenng to the surfaces of screws, idlers, Some operatiora, such as those m which dry solids beanngs, and belts. Becar : the screw cannot sweep the are loaded mto and discharged from equipment units, intenor of the transfe r tube completely, significant may mherently permit the escaps of SNM to the glovebox residual matenal may remain held up in a screw envircnment. Examples of Jus type of operation are conveyor. In all mechanicJ conveyors, dustmg can be a comnunution, blendmg, and agglomeration where quan-problem.

unes of fine powder ca - scape and accumulate on Pneumatic conveyors constitute a relatively simple glovebox mterna; surfaces ana all equipment surfaces.

way to move large quantities of d y solids. In this aperation, sobd particles suspended in air are transferred by the bulk movement of the air. Holdup p.oblems are r

5. Holdup in Calcining

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fewer than with mechanical conveyors since the transfer Holdup occurs in calcinmg when powder sticks to lines can be kept smooth and free of obstructions. Even rough surfaces or is trapp J m crevices The powder may though dustmg constitutes a problem with pneumauc become entrained in ga. streams and be deposited in conveyors, the quanuty of materi9 remaining after 5.42-3

draindo w n is nart,uily small and cicanout can be completely enclosed and sealed, dustmg can result in a achiewd tg sendmg brushes through the hnes or by significant holdup of matenal.

flushing with cleamng solutions.

Mechanic 11 vibrators that are used to classify sphen-cal particles are easily cleaned and usually have no sigmficant holdup problems.

7. Holdup in Dry Blendmg and Clawifying

8. Holdup in Packed Bed Conversion Operations Seveal factors contohute to holdup m hiendmg and classify ing equipment. One problem a,ses when drv The holdup problem that normally occu rs with particulate matenal of irregular shape a.. sue collects packed bed conversion operations is caused by the SNM and becomes packed in bnes and in mtem J recesses of that is unreacted or occluded and remains in the slag.

equipment TF s is most hkely to occur if fme particles Dus holdup matenal may be accounted for by non.

are prest m luegularly shaped particle! may become destructive analysis (NDA) or by being recovered ut trapped m wreens. Sphencal particles generally flow normal recycle or scrap-recovery operations.

freci> and dram readily f rom eq uipmen t. Ultrafine Occasionally, the re fractory hning between the powder nust be handled carefully to reduce dustmg.

packed bed and the steel containment shell for uramum Mt c hamt al bat <h ty pe blenders with mternal agn metal reduction is porous or thm, permittmg molten tators contnbute to siguiicant matenal holdup smce any tuu.n to contact the shell. This results in a " blowout" matenal that collects around the mechanical agitator and ami the release of uramum metal outside the contain.

dnve mechamsm is dif ficult to remove. Unless sealed ment shell. Spiils of this sort can result in sigmficant cove rt ae pronJed, mate nal can be dispersed as holdup of SNM in auxiliary equipment.

airbome fines-Some ceramic particles from the carbide conversion Holdup problems are nummal m hatch type blenders process ::dhere 'o or react with the walls of the graphite Anh smooth intemal surfaces, no mternal movmg p.~rts crucible. Ttus holdup matenal, which cannot be re.

and jesign that pe r mit charpng and discharpng to covered by a simple dramdown or cleanout operation, g nit, Ihc sunpe V #ne bler.oer with a full-diameter contnbutes to MUF untd the crucible is evaluated or tower is an example of tha type of blender;it is most procer d for recovery of SNM, but its contnbution is dit t icult

'o praent hoidup in the gasket area. Dust normally small.

act umulati ms on the 3.utace of a Ocone blender can easdy be ten oved with a brush or wipe.

9. Holdup in Comminution Equipment Pneumatic batch-ty pe blenders are equipped with teed and iccn\\ulauon piping that extends the surface Nearly all flow of matenal through comminution area to which reatenal can adhere. This pipmg system equipment is by gravity. Eqtupment is normally capable makas pneumatic Slenders particularly dif0 cult to clean.

of being dramed down with a mmimum of holdup.

Although these bit,ders may be designed to discharge lloidup of SNM m comnunution is most hkely to occur by gruity a hold a,roblem can result if a hne becomes m the form of anhome particles that leak from plugged or packed w th matenai that a not detected equipment or that escape dunng transfer and handhng upon dramdown.

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and collect m ventilation ducts, filters, oi on the surfaces Some,peiatmns mn bme commmution with blend-of equ2rment and gloveboxes.

mg to reduce the sue o~ particles while performmg a if gyratory or jaw crushers are used in the comminu-ouxmg cperation. Ball or ! >d nulls may be t. sed for tlus, tion operatwn, some holdup may occur on the corru.

but the large surface areas >f such miils may result in gated surfaces of the jaw faces.

>ipu0 cant mnen.d holdup af er cmptymg. The design of When SNM consists of hard fnable ceramic smter this equipmtnt makes it especi liy dif0 cult to clean.

cake or fused particles, equipment such as rota-Blendmp may also be done by sphiung and recom.

h ai.ime r mills may be used for comminution. ~

buurg of contro'le:1 quantines c f matenal. This granty.

irregular surfaces of breaker plates, rotating mecha..

How opeiation may melude mect anical aptation of the discs and hammers, and screen bus in this equipmu..

Howing stieam with an impeller o gas jet. T he principal contnbute to holdup and make draindown and cleanout sourte of matenal holdup in sphttei;is the accumulacon difficult.

or cakmg of matenal on ledge > an 1 m recesm m the c uyu.cnt Pluggng is a problem in 6Se extensiv i pipmg C. REGULATORY POSITION t

or tuhng used with mulupie sphtter. 1 or thi, reason, mesh,unc,d vibiators aie used to keep n aienal Howing in To facibtate the measurement and/or recovery of knes residual special nuclear mate ial held up in prowss The sicses,,icens, and.ui tirssifiers used to classify equipment and to improse tLe accuracy and reliabihty dry partitles an tnbu te to some hocJup of SNM.

of a physical inventory, +e amount of msidual SNM Pu tales tha t are h apped and held op in 3 reen openings held up m equipment should be nummaed. The design are dif fi ult to iemove ;uid may require sur ie mecharumal of equipment used to tury out physical or chenucal

-s ucaning. Matenal is held up m the pipmg ised with air changes on special nuclear matencJ by dry process

,lissi ne rs Uries ; ocns or sieses and air clast,Sers are operations, mc!udmg gas handbng, glovebox activiues, 156 351 5 42-4 4,

9

calcir mg, dry solids transfer, dry blendmg and classi.

2. Internal Design fymg, pr d bed conversion, and ccmminution, should incorpc

. ires that mmunue residua! boldup.

a. Eauipment should have a mimmum or mternal 8

characteristic:

S om,. ap; )pnate egwpment design features and components upon wluch process matenal can collect whose use is acceptable to the Rerdatory staff for this purpose are described m the followmg

b. Sensmg devices such as thermocouples or outer paragraphs. These features should be implemented to the detectors should be installed in a manner that nummues extent pracucable. Irnplementauon also should be con.

the amount of sohd material that can be renined on sistent with other quahty assura. ice, health, and nuclec their crfaces.

safety codes and standards that may be applicable.

c. Permanently mounted process equipment intemals

1. General Design that cannot be removed for cleaning should be designed and installed m a manner that minimizes holdup in the equipment dunng dratndown and permits cleanout if

a. Inside surfaces of equipment and doveboxes nuessam should be free of crevices, protmsions, and other irregulanties that could entrap material.

d. The inner surfaces of ducts m which deposioon of

b. Inside surfaces of equipment and gloveboxes that particulates can occur should be smooth and free of contact SNM should be selected, coated, pebshed, or recesses or other irregulanties. Vessels and transfer hnes machmed to prevent or resist the adherence of powders in which condensation. of vapors can occur should be or other dry paiucles heated and/or msulated.

c. Where possible, the lower portions of vassels such

e. Provision should be made for heatmg and purging as blenders and stcrage bms should be of conical shape pp6 cylmders and transfer lines to perrrut maumum and fitted with bottom outlets to facihtate matenal removal of the gas.

draindown and cleanout,

d. Overlapping metal surfaces m contact with process

f. Pneumatic conveyors should be Gbncated without matenal should be avoided except where sealed by intemal obstructions to the flow of air and suspended welding; internal welds should be ground flush with solids. Chargmg and emptymg ports should be designed mner surfaces. Possible excepuons are gasketed openmgs to mmianze dustmg and holdup of matenal at these such as inspetuon and cleanout doors or ports.

Poln ts.

e. The mtemal angles, comers, and recesses of

g. Trays that are used to transport matenal through gloveboxes and equipment sh, dd be designed and batch or semicontmuous muffle. type calemers should be constructed to permit complete drandown or cleanout.

designed so that they cannot be upped over or their contents spuled dunns handhng or norrial operauon.

f. Seams that promote corrosun should be avoided.

When a tray is fully loaded, the distance of the center of gravity from any side should be at least four tunes its

g. Matenals of construction that contact SNM in any distance from the bottom of the trav. Racks. carnages, form should be selected so that surfaces do not corrode, conveyors, guides, or dnve mechamsms that are used to dissolve, or erode dunng opeiation or dunng contact assist or direct the transport of trays should be designed with nnse solutions uG for cleaning. Materials fer s that individual trays cannot be upped or caused to construction of aw faca, wear bars, or bieaker plates of nde over one another.

J camnunution eqwpment should provide maximum rests-tance to pitting or ero.-

h. The use of blenders with tntemal mechamcal agitators should be avoided. If agitators are us(d. they

h. Structural mtegnty should be adequate to resist should be designed to penmt areas to dram freely and to the formation of leaks, cracks, and crevices due to presen t minimum surface for the collecuon of sohd thermal, sibratory, or other st re sse s.

Transfer an d particles.

mstrument bnes should be designed and installed so as to mininute mecharueal stresses on interconnected equip.

i. Contamment retorts or crucibks for packed bed ment.

conversen should be designed without recesses, mtemal flanges, or other uneven surfaces that would mterfere

i. Operatmg vanabies such as matenal flow rate, with the normal discharge of the bed matenal after moisture content, particle size, and vessel geometry conversion.

should be evaluated and selected to reduce undesirable formation of holdup (e g., caking or stickmg).

3. External Design

}

j. Process uruts should be closely coupled and sized t %sual access should be provided to surfaces o with minimal inte vening holdup bins and contamers, sprces where matenal is likely to accumulate Alter-consistent with good engineenna design natively, clearance should be provided so that either 5.42.5

extemal use of nondestructive assay instruments or wath appropnate seals for dnve shaft penetrations intemal probes can be used to cetect the presence of througl glovebox wa!Is.

SNM or to idendfg the location of residual matenal not y Provision should be made for charging and dis-visually accessible chatpng of dry paruct. late material in the calcining

b. Dustmg should be contreued and contamed at the operation by use of enclosed charge and discharge hnes.

Continuous calciners should be equipped with exter-charpng and discharpng ends of mechanical or pneu.

nally mounted vibrating mechanisms to ensure uni 2m matic conveyon. Pneumatic systems 60uld be leakught, flow of material through( ut the ca!ciner ana to prevent and appropnate cyclones and filters should be used at the formulauon of areas in which the material accumu-the d2scharge end to separate solids from the carner gas.

lates.

In mechamcal systems, the conveyor bodies should be enchised to reduce the dispersement of airbome SNM

,omp e en d charge and discharge hnes, matenal.

vennlated hoods, or gloveboxes should be provided for

J1 charpng, discharp ig, or handling of SNM for

c. Equipment should be arranged so that the routes blending, classifymg, and comnunution equipment. An of sohds conveyors arc as short a< pracucal and hase the exception may be mate,.al of a particle size or flow smallest number of bends and interconnections.

charactenstic such that no fmes are released dunng handhng. All openmgs, covers, or mechanical dnve

d. Exhau;t ducts should be provided on all equip.

bbding, classifying, and comminution pnen ns ment in which waste gases are generated (e g., hoods, equipment should be sealed dunng operation to prevnt doveboxes, and pneumatic transfer equipmentt The the spillage or release of SNM.

pressure mside exhaust uucts carnmg SNM particulate should be sufficiently negative to prevent the loss of

1. Piping or tubing that is extemal to blendmg or matenal by leakage to surroundmg areas.

screemr,g equipment and that may become plugged inte n lly with particulate matenal should be equipped

e. When large quantities of SNM part.culates are with euernah mounted vibratmg mect.anisms to casurt carned by exhaust gas streams. suitable devices fsuch as um orm flow of matenal and should be removable for cyclones) should be employed to separate the bulk of inspecti n nd cleaning.

such solids from thc gas streams. Prefihers at the exit poir t in gloveboxes or enclosed equipment and final tt,rts or contunment shel's used for packed bed m.

filte rs paor to release should be used to remove operanons such as uranum metal reduction should be particulates from exhaust gases. It measurable quantities dequately sealed to prevent the loss of SNM as vapor of SNM in finc particulates or vapors pass through a final dunng the reduction process. The materials used for the filter, a suitable wet scrubber should be installed in the construction of the containment shelL for unnium exhaust system to remove them. When wet scn bbers are met I reduction should be compaubic with the extemal used, consideration should be pven to instalhng suitable fum ce preheat aimosphere and with the insulating reheaters to prevent the corrosion of gas exhausters due rnatenal (refractory hning) used to separate the packed to condensation.

bed from the retort so that the shells will not corrode er warp dunng operation.

f. Devices for measuring differenual pressure should be installed around filters to indicate the accumulation

4. Design f' r Accommodating Cleanout of matenal containing SNM.

a. Equipment such as calcine rs and gloveboxes

g. Dnve inotors and gear boxes for any solids should be prouded with access ports, removable covers, conveyor should be mounted extemal to the conveyor, gg and the dnve shaft should extend through a suitable gg leak ught seal. Bearings for dnves and idlers should be protected against the entrance of sohds.

b. Access ports or removable panels should be pro-vvie d to facihtate cleaning of internal surfaces by

h. Conveyor enclosures should be equipped with

, topriate methods such as brushmg, vacuuming, wash.

vibrating devices to reduce the quantity of solijs ing, scrapmg, or nnsing to remove, dis!cdge, or dissolve adhenng after a normal draindown-SNM particles.

External surfaces of equipment installed inside

c. Equipment should be provided with tittings as i.

gloveboxes should be smooth and free of crevices, connec tions for washdown and insing of mtemal cavines, and openmgs. Dnves and power tra ns for surfaces of vessels and pipes. Air, steam, water, or process equipment should be located outside gloveboxes, appropnate chemical solutions may be used to dislodge, dissohe, or otherwise remove particulate process mate-nal, residucs, and condensed vapon remaming on inter.

Reguf atory Guwe 5.23, "In Situ Asuy of Plutomum Reudual na! surfaces of the equipment.

3 Holdup," provides additional methods arm procedures i42 6

i mviswa snould be made iur flustung and drammg

i. The nonnal contents and all nnse soluuons from u.

and for removing and collecting any of the vanous nnses rotary retort type calciners that contain htting bars or m which SNM may be entramed or dissolved. Removal Cight carnages should drain freely by ;,ravity from the of matenal from blenders, calcmers, comminuuon equip.

bottom of the calemer.

ment, or other equipment should be facihtated by d-"es that penat disassembly. Also, flush distnbution device Aauld be connected at high points in the

j. Containment shells or crucibles should be designed w 1 pemngs r aess fr thorough mecharucal transfer Ime.; or upper zones of equipment and should be cleamng such as brushing or scraping to remove or designed and a'.c 1 to allow flushing media to contact dislodge all solid particles of SNM t;1at may remain on the interior suna s and cavities of the process equip-intunal surf us after the equipment has been empued.

ment and of auxtbary devices inside the equipment.

Valves should be installed at appropnate locations in the systen for complete drdnmg.

k. Mechanical equipment, jaw faces, and breaker plates should be capable of betng disassetnbled and

e. Supplementary mechanical equipment not per-removed from crushers, disintegrators, or pulvern-S manently mounted should be capable of bemg disassem-cleaning and inspection.

bled and removed for cleanmg and in3pecuen.

f. Provisions should be made to permit venficaton that all matenal has been removed fron enclosed transfer bnes or from other eqwpment such as blender:

enched in gloveboxes.

D. IMPLEMENTATION

g. Filtei media should be removable or capable of The purpose of this section n to proside mformauon being backpurged while in position. Removable filter to applicants and licensees regarding the Regulatory media should be treated by leaching or by combusuon staff's plans for utihzing this regulatory guide.

and leaching for the recovery and determination of This guide reflects current regulatory practice. There-SNM. The design of cyclones should permit cleanout of fore, except in those cases m which the applicant proposes an acceptable attemauve method for comply-residual sobds and powders.

ing with specified portions of the Comnussion's regula-

h. Ducts should be fabncated so as to be easily tions, the method desenbed herein will be used by the disassembled. For example, taped jomts may be used to Regulatory staff in evaluating a]! heense applications facibtate disassembly.

docke:ed after pubbcation of this guide.

\\.q /a, 3ha 5.42-7