Regulatory Guide 5.26

Selection of Material Balance Areas and Item Control Areas

ML13350A206
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Issue date:	06/30/1974
From:	US Atomic Energy Commission (AEC)
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RG-5.026
Download: ML13350A206 (7)

June 1974 U.S. ATOMIC ENERGY COMMISSION

REGULATORY

DIRECTORATE OF REGULATORY STANDARDS

GUIDE

REGULATORY GUIDE 6.26 SELECTION OF

MATERIAL BALANCE AREAS AND ITEM CONTROL AREAS

A. INTRODUCTION

2. The assignment of responsibility to a single designated individual for the control of the material or Proposed (38 FR 26735) Section 70.58, the items in each area could provide more vigilant and

"Fundamental Nuclear Materal Controls," of 10 CFR effective control in each area and thus in the total plant.

Part 70, "Special Nuclear Material." would require 3. The capability for detecting the loss or theft of certain licensees authorized to possess more than one material may be improved by taking smaller material effective kilogram of special nuclear material to establish balances.

Material Balance Areas (MBAs) or Item Control Areas  !

(ICAs) for the physical and administrative control of Number of MBAs and ICAs nuclear materials. This section would require that:

The number of MBAs and ICAs established at a

1. Each MBA be an identifiable physical area such that plant will depend on considerations that are specific to the quantity of nuclear material being moved into or out the individual plants. Such consideratiors will have a of the MBA can be measured. bearing on the definition of the word "sufficient" in the

2. A sufficient number of MBAs be established so that Part 70 requirement that the number of MBAs and ICAs nuclear material losses, thefts, or diversions can be be sufficient to localize losses or thefts. It is not the localized and the mechanisms identified. number of MBAs or ICAs per se that will be sufficient to

3. The custody of all nuclear material within an MBA localize losses but the division of the plant into MBAs be thevresponsibility of a single individual. and ICAs using bases for such division which will permit

4. ICft be established according to the same criteria as identification and location of losses. Among the most MBAs except that control into and out of such areas significant considerations for establishing MBAs are would be by item identity and count for previously detection capability, physical boundaries, and the determined special nuclear material quantities. organizational structure to provide administrative control in each area. Other factors which may pertain This guide describes bases acceptable to the include material types, processes and process layout, and Regulatory staff for the selection of material balance functional locations such as laboratories, shipping and areas and item control areas. receiving areas, or storage areas.

B. DISCUSSION

Each of these factors will affect the selection of MBAs and ICAs and the effectiveness of such selecti- n The division of a nuclear plant into material balance to control material and items and to identify losses areas and item control areas can provide improved within an area. For example, if an MBA is selected to material control and accounting as follows: consist of a building in which there are two processes using different material types (such as two different

1. A loss or theft of material or of an item or items can enrichments of uranium), there may be some difficulty be identified as having occurred in a particular part of in identifying to which enrichment a MUF should be the plant so that the investigation can be more effective applied. If each process (probably in separate rooms in and the loss or th.-ft mechanism more easily identified the building) is established as an MBA, MUFs for each and corrected or counteracted. process could be identified, and losses or thefts from USAEC REGULATORY GUIES deafred oftopublished Copi the US.guides mayEergy Atomic be obtalned bv f owW

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.each process could be evaluated and investigated as quantity for a detectable loss or theft. A LEMUF that needid. In this case,-the process and the material type has been inflated, either intentionally or inadvertenify, provided a definition of the MBA. It would not be can mask a loss or theft by indcating that a MUF is not necessary for different types of material to be used in statistically significant, i.e., the MUF is the result only of the two processes for them to be established as separate the measurement error of the sstem, when in fact the MBAs. Two parallel processes using the same type of MUF includes a significant loss or theft. The material might be separate MBAs as shown in Cases II ramifications of the evaluation of MUF bnd the and V in Appendix A. Division also might be made generation of data for MUF and I ZMUF are the subjects within a process to establish MBAs that would improve of other regulatory guides. it is sufficient for the detection capability for separate parts of the process. purpose of this guide to know that the combination of a properly generated MUF and LEMUF provides a loss It may be possible to make the conversion step of a detection mechanism.

fuel fabrication process a separate MBA with a measured balance around it. The remainder of the process steps In general, the detection c.,pability of MUF and (the fabrication steps, pelletizing, sphere formation, LEMUF varies directly with the quality of the material alloying, and any other) could constitute another MBA balance measurements and inversely with the quantity of up to the point where the nuclear material is sealed in a material in a given balance. In this context, detection fuel pin, rod, etc. After sealing, the material could be capability means the threshold quantity of material that treated as an identifiable item and sent to another area the system can detect as being missing with some stated for storage or for further fabrication such as welding, probability. This capability is represented by a LEMUF

assembly, or testing. Transfer of the items from the value stated in terms of quantity, e.g., grams or MBA would be based on the material quantities as kilograms. Thtis detection capability based on a measured measured when the items were loaded. material balance is associated with MBAs rather than ICAs, since ICAs are controlled on an item basis. In an If the linal fabrication area or storage area receives ICA either all items are accounted for or they are not. If fuel from more than one loading MBA or is in a separate they are not, one or more missing items are indicated, building on the plant site, it would be designated as an and an investigation is required.

ICA using item identity and the measured quantitites from the loading MBAs for control. The selection of MBAs can affect detection capability by lowering the quantity of material in a It also may he that the conversion step of the material balance, thereby lowering the absolute LEMUF,

process is not administratively separated from the rest of since with less material there could be a smaller LEMUF

the process so that it could not be considered a separate and a greater sensitivity. This assumes that only the MBA. This would not preclude a measured balance quantity of material is changed and not measurement around that step if the produic from the step were quality.

measurable before it went into the subsequent step of the process. With proper control of the material to Examples showing the effect of this quantity change assure that all is measured once and only once as it using this assumption are presented in Appendix A of moves from process step to process step, measured this guide. The examples obviously are sinplified internal material balances can be taken around process greatly. In real situations there would be complicating segments whose inputs and outputs are measurable even factors such as discard streams, scrap removals from though separate MBAs may not be established. MBAs, recycle that might cross MBA boundaries, or uneven distribution of inventory or throughput between Detection Capability MBAs, in addition to changes in measurement quality.

Each of these could affect the selection of MBA

The basic objectives of material balance accounting boundaries.

for special nuclear material are to detect the occurrence of missing material whether it be lost or stolen, and Physical Boundaries conversely to provide assurance with a stated degree of confidence that if any material is missing it is less than a The physical boundaries of MBAs and ICAs are not threshold quantity. A prime indicator for attaining these specified in the proposed regulations except that they objectives is Material Unaccounted For (MUF). The base must be "identifiable physical areas." The boundaries for evaluation of a MUF value is the Limits of Error of .zould be no more than lines painted on the floor around the Material Unaccounted For (LEMUF). If a MUF value certaiyi parts of the process. However, if MIBA or ICA

is within the LEMUF value, it can be stated with a boundaries do not minimize the possibility of specified probability that the MUJF is due to intermixing of materials or items from different areas, uncertainties of the measurement system. The validity of either intentionally or inadvertently, the balance of such this statement depends on a number of factors, a major an area or the item control for such an area could one of which is the validity of the LEMUF itself. The become meaningless, and the location of a loss or theft LEMUF provides the limits which define the threshold of material or items might not be identifiable. Further.

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h with boundaries that do not provide physical separation out of, and within the area can be maintained to the of materials It is more difficult to discharge the custodial extent that material assigned to a given area is kept responsibility for a given area. It is too easy for material separate from material assigned to any other area. The to be moved without the proper documentation and boundaries of the MBAs must be established so that the appropriate transfer of custodial responsibility in such quantity of material moving into or out of an area can cases. Areas bound by walls, such as separate buildings be represented by a measured value. The boundaries of or rooms within a building, or by grids, such as a storage ICAs must be established so that items moving into or crib or a room divider, are well defined and the materials out of an area can be controlled by identity, count, and and items can be kept within the areas more easily. a previously measured valid special nuclear material content.

The critical factor is not the physical boundary, but the identification of an area which can be administratively controlled as a separate area around Detection Capability which either measured material balance control or item control can be maintained. This control would be related Material flows and inventories and the quality of the to the three aspects of improved material conteol and measurement of such flows and inventories should be accounting noted in the beginning of the Discussion given primary consideration in establishing material section of this guide, i.e., loss location, responsibility balance areas. Model material balances similar to those assignment, and detection capability. The boundaries of Appendix A should be prepared to evaluate the selected will depend on combinations of considerations effects of the selection of various MBAs. Such model of these three items. balances should include all of the material flow, inventory, and measurement factors thai will affect the Item Control Areas (ICAs) balance. Such factors would include recycle, discards, scrap inventory, random and systematic error effects, ICAs are differentiated from MBAs to simplify and common measurements and their covariant effect, and improve the control and accountability of identifiable changes in measurement or inventory quality as a result items. Control into and out of ICAs is required to be by of division of flows or inventories.

item identity and count and previously determined special nuclear material quantities. This excludes items Material balance areas should provide the maximum that do not have an identity that will differentiate them practicable detection capability consistent with other from other similar items, e.g., loose fuel pellets or factors such as physical boundaries or process operation unsealed, unlabeled containers of SNM. Such items and layout. To improve detection capability, could be substituted for other similar items of different consideration should be given to changes in such things SNM content or the SNM content changed so that as process layout or process operations, physical control of the material would not be maintained. boundaries, measurement techniques, and inventory Loaded and sealed fuel rods or tamper-safed sealed techniques. Consideration also should be given to containers of SNM that have been numbered or in some establishing procedures for material balances around way uniquely identified provide assurance that the process segments internal to MBAs.

quantity of contained SNM remains as previously measured. ICAs for the handling and storage of such Number of MBAs and ICAs items provide control without the need for making additional measurements for material balances. Storage The number of MBAs and ICAs established in a areas for finished fuel rods or assemblies, process s-ecific plant should be based on considerations of intermediates, or irradiated fuel assemblies could be detection capability and the physical and functional ICAs. Shipping and receiving areas could be considered aspects of the plant and material that would assist in ICAs if item integrity is maintained in those areas. identifying and localizing material losses or thefts.

C. REGULATORY POSITION

Different material should be processed in separate MBAs.

A variety of factors that are specific for individual plants and processes pertain to the establishment of The establishment of separate processes as separate MBAs and ICAs. The effectiveness of the MBAs and MBAs should be considered. Although detection ICAs in enhancing nuclear material control should be capability may not thereby be improved, the evaluated for each situation. The factors presented identification and location of losses or thefts would be.

below should be considered in the selection and Even when separate processes are not Maintained as establishment of MBAs and ICAs. separate MBAs, separate material balances should be taken around each process to identify and locate losses Physical Boundaries and possibly to enhance detection capability.

Physical boundaries of MBAs and ICAs should be Functional areas such as laboratories, receiving and established so that control of the material moving into, shipping areas, and warehouses or storage vaults should

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b with boundaries that do not provide physical separation out of, and within the area can be maintained to the of materials it is more difficult to discharge the custodial extent that material assigned to a given area is kept responsibility for a given area. It is too easy for material separate from material assigned to any other area. The to be moved without the proper documentation and boundaries of the MBAs must be established so that the appropriate transfer of custodial responsibility in such quantity of material moving into or out of an area can cases. Areas bound by walls, such as separate buildings be represented by a measured value. The boundaries of or rooms within a building, or by grids, such as a storage ICAs must be established so that items moving into or crib or a room divider, are well defined and the materials out of an area can be controlled by identity, count, and and items can be kept within the areas more easily. a previously measured valid special nuclear material content.

The critical factor is not the physical boundary, but the identification of an area which can be administratively controlled as a separate area around Detection Capability which either measured material balance control or item control can be maintained. This control would be related Material flows and inventories and the quality of the to the three aspects of improved material contiol and measurement of such flows and inventories should be accounting noted in the beginning of the Discussion given primary consideration in establishing material section of this guide, i.e., loss location, responsibility balance areas. Model material balances similar to those assignment, and detection capability. The boundaries of Appendix A should be prepared to evaluate the selected will depend on combinations of considerations effects of the selection of various MBAs. Such model of these three items. balances should include all of the material flow, invpntory, and measurement factors thai will affect the Item Control Areas (ICAs) balance. Such factors would include recycle, discards, scrap inventory, random and systematic error effects, ICAs are differentiated from MBAs to simplify and common measurements and their covariant effect, and improve the control and accountability of identifiable changes in measurement or inventory quality as a result items. Control into and out of ICAs is required to be by of division of flows or inventories.

item identity and count and previously determined special nuclear material quantities. This excludes items Material balance areas should provide the maximum that do not have an identity that will differentiate them practicable detection capability consistent with other from other similar items, e.g., loose fuel pellets or factors such as physical boundaries or process operation unsealed, unlabeled containers of SNM. Such items and layout. To improve detection capability, could be substituted for other similar items of different consideration should be given to changes in such things SNM content or the SNM content changed so that as process layout or process operations, physical control of the material would not be maintained. boundaries, measurement techniques, and inventory Loaded and sealed fuel rods or tamper-safed sealed techniques. Consideration also should be given to containers of SNM that have been numbered or in some establishing procedures for material balances around way uniquely identified provide assurance that the process segments internal to MBAs.

quantity of contained SNM remains as previously measured. ICAs for the handling and storage of such Number of MBAs and 1Cas items provide control without the need for making additional measurements for material balances. Storage The number of MBAs and ICAs established in a areas for finished fuel rods or assemblies, process si ecific plant should be based on considerations of intermediates, or irradiated fuel assemblies could be detection capability and the physical and functional ICAs. Shipping and receiving areas could be considered aspects of the plant and material that would assist in ICAs if item integrity is maintained in those areas. identifying and localizing material losses or thefts.

C. REGULATORY POSITION

Different material should be processed in separate"

MBAs.

A variety of factors that are specific for individual plants and processes pertain to the establishment of The establishment of separate processes as separate MBAs and ICAs. The effectiveness of the MBAs and MBAs should be considered. Although detection ICAs in enhancing nuclear material control should be capability may not thereby be improved, the evaluated for each situation. The factors presented identification and location of losses or thefts would be.

below should be considered in the selection and Even when separate processes are not tnaintained as establishment of MBAs and ICAs. separate MBAs, separate material balances should be taken around each process to identify and locate losses Physical Boundaries and possibly to enhance detection capability.

Physical boundaries of MBAs and ICAs should be Functional areas such as laboratories, receiving and established so that control of the material moving into, shipping areas, and warehouses or storage vaults should

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be separate MBAs or ICAs. Receiving and shipping areas Item Control Areas may be established as ICAs provided the material is not processed or subdivided and is identifiable by item and Areas designated as ICAs should contain only items in a scaled, tamper.safed condition. Warehouses and that are identified to differentiate them from other storage vaults should be considered ICAs since all similar items and are in a sealed tamper-safed condition material in storage should be identifiable by item and in that assures the integrity of prior measurements. Such a sealed, tamper-safed condition. items as loose fuel pellets or unsealed, unlabeled containers of SNM do not have identities that will differentiate them from other similar items and are therefore not acceptable for control in ICAs.

I

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APPENDIX A

EFFECT OF MBA SELECTION ON LEMUF AND DETECTION.CAPABILITY

To show the effect of MBA selection on the Case I-Inventory-Dominated Process, Total Plant MBA

LEMUF and the detection capability, several examples are presented. The examples are given for a simplified Beginning and Ending Inventories each:

plant consisting of two conversion lines and two 250 kg+/- 500 g fabrication lines. The plant may be represented by the Input and Output each:

following diagram: 30 batches @ 2 kg +/- 5 g = 60 kg +/- 27.4 g LEMUF = 2(27.4)2 + 2(500)2 =+/-708 g

- C, C2 The single total plant MBA detection capability is therefore +/-708 grams.

F, F2 Case Il-Inventory-Dominated Process, Parallel MBAs.

where: For each MBA:

Beginning and Ending Inventories each:

C1 & C2 = Conversion lines I and 2 125 kg+/- 354g /

F, & F2 = Fabrication lines 1 and 2 Input and Output each:

15 batches @2 kg +/- 5 g = 30 kg+/- 19.5 g The MBAs used in the example will be:

LEMUF = -,2(9 9.5) +2(354)2 = +/-501 Total Plant - All lines in one MBA

The detection capability has been improved from Parallel MBAs - MBA I = C1 + F, 708 grams for the single total plant MBA to 501 grams

-MBA 2 =C 2 + F 2 for each MBA. That is, a loss or theft of 501 grams in either MBA would have the same probability of being Series MBAs - MBA I = C, + C2 detected as a loss of 708 grams in the single total plant

-MBA2=F, + F2 MBA.

The examples will consider these configurations for The total plant LEMUF for the two parallel MBAs both inventory-dominated and throLllhput-dominated would'be +/-501 2 = +/-708 grams, the same as the processes. The following parameters are common to all single total plant MBA LEMUF. This is because no examples: additional measurements were made, none of the measurements were improved by dividing the plant into

1. Throughput is in 2-kg batches (Cases I, I1,and III) or two MBAs, and there were no common transfers

2"-kg batches (Cases IV, V, and VI) each of which is between the MBAs.

measured to +/-0.25% (+/-5 grams and +/-50 grams, respectively). Case III-Inventory-Dominated Process, Series MBAs.

2. Fbr simplification it is assumed that there are no discards and that there is 100% yield in the form of For each MBA:

product batches equal in size to the input batches and Beginning and Ending Inventories each:

measured to +/-0.25%. 125 kg +/-354 g

3. The inventory interval is two months. Input and Output each:

4. Beginning and ending inventories are the same size 30 batches @ 2 kg +/- 5 g = 60 kg +/- 27.4 g but do not contain any common items or material.

5. The total plant inventory is measured to +/-0.2% and LEMUF = -/2(27.4)2 + 2(354)2 = 502 g distributed so that when one-half is measured in a single MBA, it is measured to about +/-0.28%. The detection capability for Case III is essentially

6. For simplification, only random errors have been the same as for the individual parallel MBAs (Case 11).

considered. In a real situation both systematic and This would be expected because the inventory

.no random errors would need to be considered.

7. For simplification it has been assumed that there are common measurements contributing covariance effects. In real situations such covariance effects would need to be considered.

dominates and it is divided in half in each case. The total plant LEMUF does not change, even though there have been additional measurements made, i.e., for the transfer between MBAs. This transfer measurement is assumed to be the same for both MBAs. That is, the output

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measurement of MBA I is the input measurement of combined LEMUF for the two MIBAs would be +/-')08 MBA 2. When the uncertainties of the two MBAs are grams but the MUF (i.e., material stoien) would le 1002 combined to obtain the total plant MBA uncertainty, gram!, and probably would trigger an investigAtiin. Th7 this transfer measurement is common and drops out of loeatl'or of the loss within thp p!"'lnt in this case n:ay nol'W

the equation for tile total plant. be known because the MUF of the individual MBAs may not Lave exceeded the LEMUF.

TFlhe assumpticn in this case was that the transfer measurement is as good as the input and product Case IV--Throughput-Doniinated Process. Total Plant measurement s. To thie extent that this is not true, the MBA

individual MBA LEMUF is increased and the detection capability decreased. This effect becomes more Beginning arid Ending Inventory each:

pronounced as the absolute uncertainty of the transfer 50 kg +/- 100 g measurement increases. For example, if the uncertainty Input and Outptut each:

of the transfer measurement were thie same as that of the 30 batches 6129 kg +/- 591 g = W00 kg +/- 27- ii inventory, i.e., 60 kg +/- 354 grams (3% instead of thc.

previously used 0.25%) the LEMUF of the individual LEMUF = vF2(274)2 + 2(l00)` :+/- 4 3

1 g MIBAs would be +/-614 grams. There would still be sone advantage in dividing the plant into the series MBAs but Case V --Throughput-Dominated Process, Parallel M, As not as much as when the transfers 1.:1ween MBAs could be measured with a precision approaching that of the For each MBA:

input and produrt measurements. Beginning and Ending Inventories each:

25kg +/- 71 g It can he seen froin Cases 1. II, and III that striking a Input and Output each:

balance around portions of the inventory will increase 15 batchesV20kg +/- 50g 300 kg +/- 194 g lhe detection capability tor each portion, but not for the total plant. LEMUF = N[2(1l.4)* 4 2(71)2 2'2 g In Case I, if anl actual loss of 708 grams had The individual MBA detection capability has been occurred, it would be expected that the MUF would improved from 412 grams to 292_rams. The total plant exceed the LEMLUF of +/-708 grams part of the time. The LEMUF will not change (9-_2,v2 = +/-413) hecause no probability of the M*UF exceeding tile LEMUF in this additional measurements were made nor were anvAdlt case could he calculated. When the MUF exceeds the improvements made in the measurement of any of thm LEMUF, an alarm is sounded and the high MUF is balance components.

investigated as occurring somewhere in the total plant.

Case VI-Throughput-Dominated Process, Series MBAs In Cases If and II the balance is taken around smaller areas so that the detection capability is improved For each MBA:

Beginning and Ending Inventories each:

to 502 grams for each area. If a loss or theft of 708

25 kg +/- 71 g grams were to occur in either area, it would have a higher probability of detection since the LEMUF is only Input and Output each:

+/-501 grams. In addition, if such a loss did occur, the 30 batches QV20 kg +/- 50 g = 00 kg +/- 27 4 g area in which it occurred would be shown by the high MUF in that MBA so that the investigation could be LEMUF = x/2(274)2 + 2(71.)- = a400 g confined to the smaller area. In order for a person to steal 708 grams of material with the same probability of There has been little gain in the delvction capabiliy success. i.e., being undetected, as in a single total plant over a total plant MBA because t0he t.hroughpul is lie MBA, portions of the material would have to be same for each of the two ser~es MBAs as t:or a siigl, total plant MBA. The little gain that is realize"\ is due to the removed frmm two different MBAs or over a longer gain obtained by dividing the inventory in half. In ad'di- period of time in the same MBA. This would expose the (ion, if the transfer measurement between MGAs in Case thief to an increased probability of detection by the VI is not as good as the input and produc; measurements plhysical protection surveillance and alarm systems.

there may be a loss of detection capability. For example, if the precision of the transfer measurement for each If a person wvere to steal 501 grams from each MBA batch is +/-0.5% instead of +/-0.25%,, the uncertainty of this of Case II of Ill the detection capability would be the total transfer measurement becomes 600 kg +/- 547 grams same for each NIBA as for theft of the 708 grams from and the LEMUF for each MBA becomes +/-780 grams.

the single total plant MBA. The total quantity stolen, This is a poorer detection capability than the 412 grams however, would he so large that the total theft would for the single total plant MBA. The effect of this transfer have a higher probability of detection upon calculation measurement is cuore pronounced here than in Case ll1 of the balance for the entire plant. In-the example, the where the inventory dominiate

d. a

5.26.6