ML20057D858
| ML20057D858 | |
| Person / Time | |
|---|---|
| Issue date: | 09/16/1993 |
| From: | Greeves J NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| Shared Package | |
| ML20057D855 | List: |
| References | |
| REF-WM-3 NUDOCS 9310060077 | |
| Download: ML20057D858 (33) | |
Text
_ _
1I 1
SEP 161993 l
ATTENTION: Commission Licensees
SUBJECT:
REISSUANCE OF PROPOSED CONCENTRATION AVERAGING AND ENCAPSULATION TECHNICAL POSITION, REVISION IN PART The regulation, " Licensing Requirements for Land Disposal of Radioactive Waste," 10 CFR Part 61, establishes a waste classification system based on the concentration of specific radionuclides contained in the waste. The regulation also states, at fl61.55(a)(8), that, "the concentration of a radionuclide [in waste] may be averaged over the volume of the waste, or weight of the waste if the units [on the values tabulated in the concentration tables) are expressed as nanocuries per gram" (text added for clarity).
On June 26, 1992, Comission licensees were sent copies of a proposed
" Concentration Averaging and Encapsulation Technical Position, Revision in Part," on which comments were solicited. A notice of availability of the
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proposed Technical Position was also published in the Federal Reaister on June 30, 1992 (57 fB 29105).
In response, nineteen comment letters were received suggesting the need for further expansions of and several modifications to the Technical Position. Consideration of these coments has resulted in modifications and a further expansion of the Technical Position.
The modified Technical Position 'is enclosed (Enclosure 1)'and, because of the significant additions and interest expressed by commenting parties, is agair, being issued for comment in proposed form. Also, enclosed (Enclosure 2) is a sumary of the major comments together with the Nuclear Regulatory Commission staff's responses.
Coments on this revised Technical Position should be received prior to November 15.1993, and sent to Chief, Rules Review and Directives Branch, U.S. Nuclear Regulatory Commission, Washington, DC 20555. Questions may be referred to William Lahs, U.S. Nuclear Regulatory Commission, Nail Stop SE-4, One White Flint North, Washington, DC 20555, telephone (301) 504-2569.
931006o077 930914 U
Consission Licensees [
A final technical position will be issued following NRC staff review of the comments received. The information collections contained in the Technical Position have been approved under the Office of Management and Budget number 3150-0014.
O Q __. -
i f
l b
(
g John T. Greeves, Director Division of Low-Level Waste Management and Decommissioning Office of Nuclear Material Safety and Safeguards
Enclosures:
As stated
-,q BRANCH TECHNICAL POSITION ON CONCENTRATION AVERAGING AND ENCAPSULATION INDEX i
+
Page A.
INTRODUCTION............................................................
1 B. DISCUSSION..............................................................
2 C.
REGULATORY P0SITION.....................................................
2 l
Volumes-and Masses for Determination of Concentration.................
2 C.3 Mixing of homogeneous waste types or streams...........................
4 J
Solidi fied and absorbed 11guids........................................ 5 Mixing of activated materials or metals, or components incorporating radioactivity in their design.......................... 5 8
Averaging involving predominant gamma-emitters.................. 5 k.eraging of sections or pieces of larger components cot.taining Co-60, Nb-94, or Cs-137/Ba-137.....................
6 Averaging involving radionuclides other than primary gamma-emmitters...............................................
7 Averaging involving sections or pieces of larger components containing other than primary gamma-emitters................... 5 Mixtures containing multiple radionuclides...................... 7 Example 1........................................................g Example 2....................................................... 9 Example 3......................................................
12 Cont ami nated materi al s................................................ 13
)
Averaging involving predominant gamma-emmitters................ 13 Averaging of sections or pieces of larger components containing Co-60, Nb-94, or Cs-137/Ba-137................
14 Averaging involving radionuclides other than primary g amma-e mmi t t e r s.............................................. 14 Averaging involving sections of pieces of larger contaminated items or components containing other than primary gamma-emmi tters............................. 15 1
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~~1l 7-INDEX (Continued)
Mixtures containing mul tipl e radionucl ides..................... 15 Mi xi ng o f cartridge fil ters......................................... 16 Averaging involving predominant gamma-emmitters................ 16 Averaging involving radionuclides other than primary g amma-emmi t t e rs.............................................. 17 Mixtures containing mul tiple radionuclides..................... 17 E x amp l e........................................................ 18 Waste in high-integrity containers...................................
18 Encapsul ation of solid materi al...................................... 19 Mixing of dissimilar waste streams (different waste types)...........
19 Alternative provisions...............................................
20 Summary Tab1e........................................................
21 APPENDIX C POSITION ON ENCAPSULATION OF SEALED SOURCES Als OTHER SOLID LOW-LEVEL RADI0 ACTIVE WASTES.........................................
22
9 t
IPronosedl Technical Positior,on Concentration Averaaina and Encaosulation A.
INTRODUCTION The overall acceptability of low-level radioactive waste disposal requires a performance assessment of the disposal facility which demonstrates compliance with the performance objectives stated at 561.41.
In addition, to provide protection for individuals from inadvertent intrusion (i.e., 561.42), the suitability of radioactive waste for near-surface disposal necessitates the proper classification of that waste. The regulation, " Licensing Requirements for Land Disposal of Radioactive Waste," 10 CFR Part 61, establishes a waste classification system based on the concentration of specific radionuclides contained in the waste. The regulation also states, at 5561.55(a)(8),that, "The concentration of a radionuclide (in waste] may be averaged over the volume of the waste, or weight of the waste if the units [on the values tabu-lated in the concentration tables] are expressed as nanocuries per gram" [ text added for clarity).
A technical position on Radioactive Waste Classification was initially developed in May 1983. This initial position included a section, "Concentra-tion Volumes and Masses," which provided guidance to waste generators on the interpretation of 5561.55(a)(8) as it applies to a variety of different types and forms of low-level waste. This position expands upon, further defines, and replaces that guidance which was provided in Section C.3 of this original 1983 Technical Position. The other sections of this 1983 Technical Position remain in effect with the exception of the corrections noted in the footnote below.' The recommendations and guidance provided in this Section C.3 revi-sion represent acceptable methods by which specific waste streams or mixtures of these waste streams may be classified against the tabulated concentration values defined in Tables 1 and 2 of 561.55. The guidance may not specifically address all unique waste types or waste packaging methods. Other provisions for the classification of these specific wastes or waste mixtures may be The following corrections should be made to the May 1983, Rev. O, Technical Position:
(1) pg.1,1st para., 4th line -- delete the words, "or proces-sor"; and (2) pg. 6, 4th line and pg.12, 2nd para., 5th line -- replace
" biannual" with " biennial".
1 e
l deemed acceptable as discussed under the " Alternative previsions" paragraph of I
this revision.
L B.
DISCUSSION l
Each shipment-of radioactive waste to a'-licensed operator of a land disposal facility must be accompanied by a shipment manifest.- In the manifest,:the shipper / consignor-licensee must classify and clearly identify waste as Class-A, Class B, or Class C, in accordance with 161.55. Determination of the classification of waste involves two considerations. First, consideration must be given to the concentration of long-lived radionuclides in the waste l
with respect to the values in Table 1 of 561.55. Second, consideration must be given to the concentration of short-lived radionuclides in the waste with
-l respect to the values in Table 2 of 161.55.
i Waste-is determined to be generally unacceptable for near-surface disposal if ~
j l
it contains any of the radionuclides listed in Tables 1 and 2 of 161.55 in -'
concentrations exceeding the applicable limits established for the indvidual radionuclides.
)
l C.
REGULATORY POSITION
]
l-l l
I 1
l 3.
Volumes and Masses for Determination of Concentration
- i Paragraph 61.55(a)(8) states that, for the purposes of waste classification,
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the concentration of a radionuclide may be averaged over the volume of the waste, or the weight of the waste for those concentration units in 161.55 Table I that are expressed as nanocuries per gram. This requirement needs interpretation because of the different types and forms of low-level waste.
Principal considerations include:
(1) whether the distribution of
{
It should be noted that wa'ste acceptance requirements for Agreement State disposal facilities ~-(e.g., requirements for encapsulated wastes or acti-vated metals) may differ from this guidance. Waste generators should con-sult with disposal site operators or appropriate regulatory authorities.
prior to classifying these wastes.
2
1 4
i
. i i 1 radionuclides within the waste can be considered to be reasonably homogeneous; (2) whether the "as-generated" waste has been processed and, if so, what is the mass / volume of the processed waste; (3) whether the waste includes mixtures of various waste types (i.e., a waste stream with a particular set of physical characteristics); (4) whether the waste includes mixtures of the same waste type but at differing radioactivity concentration levels; and (5) whether the volume of the waste container, if used to represent the volume of the waste, is significantly larger than the volume of the waste itself, and the differential volume consists largely of void space.
With respect to the above considerations, many waste types may be considered to be homogeneous for purposes of waste classification. A homogeneous waste type is one in which the radionuclide concentrations are likely to approach uniformity in the context of the intruder scenarios used to establish the values included in Tables 1 and 2 of 961.55.
Such waste types would include, for example, spent ion-exchange resins, filter media, solidified liquid, eva-porator bottom concentrates, or contaminated soil. Contaminated trash waste,3 which is composed of a variety of miscellaneous materials, may be considered homogeneous for purposes of waste classification when placed in containers.
To the extent that contaminated trash and contaminated soil are reasonably packaged in a disposal container (i.e., it90% fill), the volumetric-averaged concentration of radionuclides in these waste types can be based on the fill-volume of the container. Alternatively, the volume of the waste can be calculated from the weight of the container contents divided by the density of the contents. A representative density based on a representative distribution of materials as they occur in waste may be used.
For spent ion-exchange resins and filter media, care needs to be taken to differentiate between the volume of the waste form and the volume of the wasta container. Although free volume should be reduced to the extent practicable, these wastes may be contained within a disposable demineralizer, liner, or high integrity container (HIC) with some waste-free volume.
In such cases, the volume or weight used for waste classification should be the displaced or bulk volume (interstitial space may be included) or dewatered weight of the resins or filter media rather than the gross internal volume of the container or the weight of the resins prior to dewatering.
3
~
M The followina naraaraohs nrovide auidance on snecifically accentable classifi-cation or encansulation oractices. Other orovisions for classification or t
encaosulation of snacific waste may also be deemed accentable' as discussed in the " Alternative orovisions" naraaraoh at the end of this section.
Mixina of homoaeneous waste tvoes or streams i
')
Mixing of similar homogeneous waste types (e.g., spent ion-exchange resins or contaminated soils) is permissible. However, mixing with the sole intent'to dilute radionuclide concentrations to lower a waste's classification is not permitted. Note: A designed collection of homogeneous waste types from a number of sources within a licensee's facility for purposes of operational efficiency or occupational dose reduction is not considered " mixing" for. pur-i poses of this position. Under this guideline the classification of the mix-l ture using the sum of fractions rule specified in 161.55 should be based on i
1 either (a) the highest nuclide concentrations in.any of the' individual waste i
types contributing to the mixture;-or (b) the volumetric-or weight-averaged
- l nuclide concentrations of the mixture, provided that the concentrations of the I
individual waste type contributors to the mixture are within a factor.of 10 of the concentration of the resulting mixture.
j Mixing of dissimilar homogeneous waste streams may also be permissible but i
should receive appropriate regulatory approval under the " Alternative l
provisions" paragraph of this position.
In any of the above cases, in accordance with Section III of Appendix F to 10 CFR Part 20, the licensee classifying the waste must have in place a quality control program to ensure compliance with the waste classification provisions of $61.55. As part of this quality control program, if the classification of a mixture is based on the volumetric-or weight-averaged nuclide concentration af the mixture (e.g., as allowed under (b) above), the licensee responsible for classification of the waste should prepare, retain with manifest documentation, and have available for inspection, a record documenting the licensee's waste classification analyses.. This record or analyses should be sufficient to show that the mixing was not undertaken solely to lower the classification of a waste stream contributing to the mixture.
4
~
-- O
1 Solidified and absorbed liouids J
Classification of evaporator concentrates, filter backwashes, liquids or ion-exchange resins solidified in a manner to achieve homogeneity and meet the stability criteria of 561.56 should be based on solidified nuclide activity divided by the volume or weight of the solidified mass.
Because absorbed liquid wastes do not appreciably bind nuclides, classification of absorbed liquids should be based on the adsorbed activity divided by the volume or mass of the liquids prior to absorption.
Mixino of activated materials or metals. or comoonents incorooratino radioactivity in their desian For neutron-activated materials or metals, or components incorporating radioactivity in their design, the waste classification volume or weight should be taken to be the total weight or displaced volume of the material, metal, or component (i.e., major void volumes subtracted from the envelope volume).
Mixtures of these materials, metals, or components in a disposal container or liner are permissible.
In determining the classification of such a mixture, it is always permissible to conservatively base the mixture classification on the highest classification associated with any piece, section or component within a disposal container or liner.
It is also permissible, under the fol-lowing constraints, to average the concentrations of the radionuclides listed in 661.55 Table 1 and Table 2 over the contents of the disposal container or liner. Because of the potential non-homogeneity of the waste, the classifica-tion of the combined waste may be affected by whether or not the waste con-tains the predominantly gamma-emitting nuclides (Co-60, Hb-94, or Cs-137/Ba-137).
In determining the classification of the container / liner, one or more of the following paragraphs may apply as indicated in the logic diagram (Figure 1) on pages 10 and 11.
Averaoino involvino oredominant aamma-emitters For the purpose of classifying a mixture of items or components containing Co-60, Nb-94, or Cs-137/Ba-137, their individual nuclide concentrations may be 5
g i
i i
j based on the volumetric-averaged concentration of the combined materials provided that the concentrations within the individual items ~ or components in j
the disposal container or liner are within a factor of 1.5 of the respective
}
averaged concentration value for.each nuclide. Averaging is always allowed I
for a specific gamma-emitting nuclide if its activity within an item or component is less than 37 MBq (1 mC1).
l Averaaino of sections or nieces of laroer comoonents containino Co-60. Nb-94. or Cs-137/Ba-137 Individual sections of pieces of larger components that'may result free operational considerations (e.g., packaging for transportation) should be considered as discrete items if:
(a) the volume of the pio:a or section is less than one-hundredth of a cubic 3
3 foot (0.01 ft ) or 0.00028 cubic meters (0.00028 m ) -- such a-piece will typically weigh less than ten pounds (10 lbs) or 4.54 kilograms (4.54 kg), and (b) the g cific nuclide activity in the piece or section is greater than the respective value shown in Table A.-
Furthermore, if all sections or pieces of the whole component are ng1 contained in the same disposal container, regardless of their volume or activity, they should be considered as discrete items in classification determinations.
TABLE A Activity Levels in Individual Sections or Pieces of Larger Components Potentially Requiring Their Piecemeal Consideration in Classification Determinations.
For Waste For Waste Classified as Classified as Nuclide Class A or B Class C Co-60
>26 TBq (700 C1)
N.A.
Nb-94
>37 MBq (1 mci)
>37 MBq (1 mci)
Cs-137/Ba-137
>111 MBq (3 mci)
>1.1 TBq (30 C1) 6
..n.
~
-n e,-
-sw,
--m ma 4
-4 i
Averacino involvino radionuclides other than crimary cam a-emitters For the purpose of classifying a mixture, the concentratit.,ns of all 561.55 tabulated radionuclides in the disposal container or liner, other than Co-60, Nb-94 or Cs-137/Ba-137, may be based on the volumetric-or weight-averaged concentrations of the combined materials.
In this case, all the concentra-tions of the " classification-controlling" individual nuclides within all the 3
individual items should be within a factor of 10 of their respective averages over all items in the mixture.
Averacino involvino sections or oieces of larcer comoonents containino other than crimary camma-emitters Individual sections or pieces of larger components in a disposal container that may result from c?erational considerations (e.g., packaging for transpor-tation) should be considered as distinct items if the nuclide activity in the piece or section exceeds the appropriate value indicated in Table B.
Mixtures containino multiple radionuclides For activated materials, metals, or components containing combinations of tabulated nuclides, the sum of the fractions rule described in 661.55(a)(7) would apply. This sum-of-the-fractions rule would involve summing the fractions of the appropriate 561.55 Table 1 or 2 concentration values as described in 9561.55(a)(7). The sum of the fractions rule could involve summing the fraction of the appropriate 561.55 Table 1 or Table 2 concentration values associated with the predominately gamma-emitting nuclides and the fractions of tabulated concentrations associated with the oth w 3
A " classification-controll.ing" nuclide is one which is contained in waste in concentrations greater than 0.01 times the concentration of that nuclide listed in Table 1 or 0.01 times the applicable Class-dependent concentra-tion of that nuclide in Table 2, Column 2 or 3.
Note that a nuclide may be significant for reporting purposes under Section 4 in the May 1983 Technical Position and yet not be a " classification controlling" nuclide.
7
I 1 [
]
i l
TABLE B i-l-
Activity Levels in Individual Sections or Pieces of Larger Components.
l Requiring Their Piecemeal Consideration in Classification Determinations.
For Waste-For Waste j
Classified as-Classified as Nuclide Class A or B-
~ Class C l
>0.3 TBq (8 C1)
N.A.
>0.04 TBq (1 C1)
>0.4 TBq (10 C1)-
t i
j Ni-5g
=>0.15 TBq (4 C1)
>1.5 TBq (40 C1) i Ni-63.
>0.26 TBq (7 C1)
>55 TBq l
(1500 C1) i i
Alpha emitting TRU.with half-life -
>111 MBq (3 mC1)
>1110 MBq greater than 5 years (excl. Pu-(30 sci) 3 241 and Co-242) 1 l
j nuclides. The respective fractions contributing to the sum.can bra calculated' i
by using the " highest concentration" existing.in any item within the mixture or, if applicable,' the concentration determined by usinC the " averaging" 4
-i methods described previously.
I i
Independent of the method chosen, in accordance with Section III of Appendix'F l
to 10 CFR Part 20, the licensee classifying the mixture of items must have in i
place a quality control program to ensure compliance with the waste classi-i fication provisions of 561.55.
's part of this quality control' program, if
{
the classification of the mixtura of items is based on'the volumetric-or weighted-averaged nuclide concentrations of the disposal container / liner i
contents, as allowed above, the licensee responsible for classification of the-j-
waste should prepare, retain with manifest documentation, and.have available l
for inspection, a record documenting the licensee's waste classification anal-
}
yses. This. record or. analyses should be sufficient to show that the averaging of concentrations over all the contents in the disposal container / liner was not undertaken solely to lower the classification if any of the. individual items in the disposal container.
1 B
e
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1 Examole 1: Three equally sized control rod blades are contained in a liner.
3 3
The blades (0.6 ft or 0.017 m ) respectively contain concentrations of Nb-94 which are 0.9, 0.7, and 0.5 of the 561.55 Table 1 value for Nb-94 of 0.2 curies per cubic meter. The blades also contain Ni-59 in concentrations of 44, 22, and 11 curies per cubic meter. These concentrations are 0.2, 0.1, and 0.05 of the f61.55 Table 1 value for Ni-59 of 220 curies per cubic meter.
The Nb-94 concentrations in the three blades are all within a factor of 1.5 of the average concentration within three blades (i.e., 0.14 curies per cubic meter). Likewise, the Ni-59 concentrations in the three blades are all within a factor of 10 of the average concentration within the three blades (i.e., 26 curies per cubic meter). The sum of the fractions for the blades in the liner would be calculated by summing, 0.7 (the averaged Nb-94 fraction for the blades) and 0.12 (the fraction for the Ni-59 activity averaged over all three bl ades). The sum, 0.82, would qualify the liner as containing Class C waste.
Examole 2: The cruciform section of a boiling-water reactor control rod blade (0.6 ft3 (0.169 m ) and 200 lbs. (90.8 kg)) contains a Nb-94 concentration 3
of 0.16 curies per cubic meter, a Ni-59 concentration 22 curies per cubic meter, and a Ni-63 concentration of 5000 curies per cubic meter. The blade, as a whole, would be classified as Class C waste (i.e., Nb-94 fraction (0.8) +
Ni-59 fraction (0.1) - 0.9, using the sum of the 561.55 Table I fractions; the Ni-63 concentration is less than the respective Table 2, column 3 value). The blade, however, is sectioned into four equal pieces to facilitate shipment.
The " hottest" piece contains 80% of the blade's activity. This piece would contain a concentration of Nb-94 above the 661.55 Table 1 value. However, if all pieces of the blade are contained in the same disposal container, the con-tainer could be classified as Class C waste, based on the blade as a V.cie, 3
because the volume of each piece exceeds 0.01 cubic feet (0.00028 m ).
9 i
s l
}
aunvEYITEM(@
i h
k oe=rmes si.m Nucede Concentregona And Presenne or -
TeWe 1 & 2 Values i
CW No' item i
P7
,,v-Are Aedwnee in No i
Pieces < Table A Are No venu e ForN E M Pl****
- 01 ft 8 ?
(sesed on i m
Survey)?
4,..
Yes Yes Are 1 I I f Aconnes in Plecos < Table No Survey Pieces i
Values For or p InerWuesy Emreers(Based tem Survey I I Yes Are N IR As Ed N l
Of Ortginal Yes
< Table A & B Valuee J
item Put in 1[ -
N i
Peekapet No
[
Pleses)?
i r-v UseConsentretene of 1 f Originalitem(s)1.e.,
+
Distnetih me No ConeMar Originalllem As idenillied That Must seene For Concentremen no Con dered For IN E*'
4 Detonninesens Clasefying A
+=
Closeulesson Mtunne Of Westee in A Disposal W
N h
r To nemt page FIGURE 1 LOQlC DLAGRAM FOR CLASSIFYING WASTE COMPRISBNG ACTIVATED METAL OR COMPONENTS CONTAINING RA0lOACTIVirY IN THEIR DESIGN 10
I f we here Se More No Then 1 Disenetitem In A Disposal Containerfunw?
Yee If Determme Average Freetonal Concentre8ene For C
Tame 1 and 2
- Clasemoeden contrehng" Nucedes Yeo 1 I Indicates That is le R Ch Sum of le N FenelMeTo Based on E of Preceone to Frecuene 11.0 FeaaMeTe h
invoere An y, m Reconomute Anemedvs Groeter Then TW The Mbeture?
Provimien That Indicated g
ByThe TabW Column Chosen j
oris GTCC Yes I
Yee Are No 3 g Freedonal Consentregone Of CN!$$ umesp "Closee ' - " NueEden P6 4 y Sesed WIedm Delhed of On Alsemate Average Le.:1.8 for Provimien Ni>=44, Ce-137; 10 ForOster Nue8 des?
- IMPORTANT: Note that averaging is always allowed if the specific gamma-emitting nuclide activity j
within an item or component is less than 37 MBg (1 mci) i Yes 4
1 f unertPestiage Can se Classmed Bened On m
i
.55 i
Table And Column Seleedon 11 4
y
l Exaanle_1: A liner contains 4 local power range monitor (LPRM) strings.
Note:
In actual cases, liners could contain more than this number. Each string has a volume of 0.1 ft3 (0.0028 m ) and weighs 50 lbs '(22.7 kg). The 3
activity of the principal " classification controlling" nuclides in each string are shown below along with the nuclides concentration expressed as a fraction (frac) of the appropriate 561.55 Table 1 or Table 2, Column 3 concentration values.
IJanssa IJanss2 IJaalas IJans#4 Avs.
- SEME CL Ana G
Aus C1 Ana GL Aus mes o.oese e.7 o.coes o.s3 o.coess e.as-e.ooes e.es o.es Ni-se o.12 o.2e o.co e.15 o.1 0.17 0.13 c.12 o.19' c.14 o.o2 o.oo o.ets o.o?
o.e 7 e.se o.es o.oo a.os TAmal WAR.
1.oe o.7s e.e7 1.2 o.96
?
Nide Ia.8 e.o2 13.3 o.6e 13.73 4.81 22.8 1.12 -
o.e6 TAE22WAE.
o.o2 o.Se 0.88 1.12 0.Bo The strings need to be cut into three pieces for packaging and this sectioning leads to essentially all of the activity being contained in a piece which has 3
a volume of 0.017ft3 (0.00048 m ) and weighs 8.5 lbs (3.9 kg)..
t It would be permissible to average the Nb-94 concentration over all four strings since no string contains more than 37 MBq (1. sci) of Nb-94.
Furthermore, all the concentrations of the individual strings are within a 3
factor of 1.5 of the average concentration (i.e., 0.69 x 0.2 C1/m - 0.138 3
C1/m ).
Likewise the. concentrations of the other tabulated nuclides are within a factor of 10 of their average concentrations.
If the strings were shipped as a whole, the waste would be classified as Class C sinc'e the sum-of-the-Table 1 fractions is 0.96 and the Ni-63 concentration is less than (i.e..
0.89 times) the Class C limit of 7000 curies per cubic meter. Although the cutting' operation could increase concentrations in the " hottest" piece by about a factor of 6, this sectioning would not affect the classification of the waste since (1) the volume of the " hottest" piece is greater than 0.0!f t' (0.00028 m ), (2) the largL,t Nb-94 activity in any piece, 0.5 act, is less 3
12 y
-._w
+
-~u v
,.~,-.,.s-w.,
than the 1 act value in Table A, (3) the activities of the other nuclides. in j
the " hottest" piece are less than Table B values, and (4) all pieces of the l
sectioned string are placed in the same disposal-container.
Contaminated materials i
i
]
Contaminated materials typically involve components or metals on which
?
radioactivity resides near the surface in a fixed or removable condition.
j Classification of individual items may be determined by representative swipes j
or radiation survey measurements from which.the total activity of radionu-clides may be estimated through the use of scaling factors.
In these' cases,.
the volume or weight of the contaminated item should be the total weight or displaced volume of the item (i.e., major void volumes subtracted from j
envelope volume).
i l
8 l
Mixtures of contaminated materials in a' disposal container. are permissible.
j In these situations, the total activity of contained radionuclides may also be i
determined by representative swipes or radiation survey measurements of the f
container's contents. The volume or weight of the mixture should be the total j
weight or displaced volume of all the material contributing to the mixture.
t In determining the classification of a mixture of contaminated materials, it l
1s always permissible to conservatively base the mixture classification on j
the highest classification associated with any piece, section',.or component l
within a disposal container.
It is also permissible, under the following con-l straints, to average concentrations of the radionuclides listed in.161.55 j
Table 1 and Table 2 over the contents of the disc sal container. Again, l
because of the potential non-homogeneity of th-waste, the classification of l
the combined waste may be affected by whether' e not the contaminated waste l
contains the predominantly gamma-emitting nuclides _ (e.g., typically, Co-60 and j
Cs-137/Ba-137).
In determining the classification of the container, one.or more of the following paragraphs may apply.
Averaaina involvina credominant a-- -emitters i
j For the purpose of classifying a mixture containing Co-60 or Cs-137/Ba-137
[
contamination, their individual nuclide concentrations may be based on 13
=
1-.....
1 the volumetric-averaged concentration of the combined contaminated materials provided that the concentrations associated with the individual items in the disposal container are within a factor of 1.5 of the respective averaged concentration value for each nuclide. Averaging is always allowed for a specific gamma-emitting nuclide if its activity on a contaminated item is less than 37 MBq (1 mci).
Averaoina of sections or oieces of larcer comoonents, l
containina Co-60. Nb-94. or Cs-137/Ba-137 l
Individual sections of pieces of larger components that may result from operational considerations (e.g., packaging for transportation) should be considered as discrete components if:
(a) the volume of the piece or section is less than one-hundredth of a cubic 3
3 j
foot (0.01 ft ) or 0.00028 cubic meters (0.00028 m ) -- such a piece will typically weigh less than ten pounds (10 lbs) or 4.54 kilograms (4.54 kg),
And; j
(b) the specific nuclide activity contaminating the material or component would be greater than the respective values shown in Table A; or Furthermore, if all the contaminated sections or pieces of the whole component are agi contained in the disposal container, regardless of their volwa or activity, they should be considered discrete items in classification determinations.
Averacino involvina radionuclides other than crimary camma-emitters For the purpose of classifying a mixture, the concentrations of all the 561.55 tabulated radionuclides in the disposal container, other than the Co-60, Nb-94, and Cs-137/Ba-137, may be based on the volumetric-or weight-averaged concentrations of the combined materials.
In this case, all the concentra-tions of the " classification-controlling" individual nuclides within all the contaminated items should be within a factor of 10 of their respective averages over all items in the mixture.
14 s-
-e Averaaina involvina sections or oieces of laraer contaminated itemi or comoonents containino other than crimary camma-emitters Individual sections or pieces of larger contaminated items or components in a disposal container that may result from operational considerations (e.g.,
packaging for transportation) should be considered as distinct components if a
the specific radionuclide activity on the contaminated piece or section exceeds the appropriate value in Table B.
Mixtures containino multiole radionuclides For contaminated components or metal containing combinations of tabulated nuclides, the sum of the fractions rule described in 5561.55(a)(7) would apply. This sum of-the-fractions rule would involve suming the fractions of the appropriate 661.55 Table 1 or 2 concentration values as described in 6561.55(a)(7). The sum of-the-fractions rule could involve summing the frac-tions of the appropriate 561.55 Table 1 or Table 2 concentration values asso' ciated with the predominately gamma-emitting nuclides and the fractions of tabulated concentrations associated with the other nuclides. The respective fractions contributing to the sum can be calculated using the " highest concentration" existing in any item within the mixture or, if applicable, the concentration determined using the " averaging" methods previously described.
Independent of the method chosen, in accordance with Section III of Appendix F to 10 CFR Part 20, the licensee classifying the mixture of contaminated mate-rials must have in place a quality control program to ensure compliance with the waste classification provisions of 561.55. As part of this quality con-trol program, if the classification of the mixture of contaminated materials is based on the volumetric-or weighted-averaged nuclide concentrations of the disposal container contents, as allowed above, the licensee responsible for classification of the waste should prepare, retain with manifest documenta-tion, and have available for inspection, a record documenting the licensee's waste classification analyses. This record or analyses should be sufficient to show that the averaging of concentrations over all the contaminated mate-rial in a disposal container was not undertaken solely to lower the classi-fication of any specific contaminated item in the disposal container.
15 C
3 Mixina of cartridae filters The classification of cartridge filters should be based on the nuclide activity contained on the filter. divided by the displaced volume (interstitial-space within the filters may be included) or weight of the filter..
Mixing of multiple cartridge filters in a disposal container or liner is permissible. 'In determining the classification of the multiple filters, it is always permissible to conservatively base the classification on the~ highest j
classification associated with any single filter. -It'is also permissible, j
under the following constraints, to average the concentrations of radionu-l clides -listed in 661.55 Table 1 and Table 2...Because of the potentially j
non-homogeneity of the filters,' the classification of'the combined filters may j
be affected by whether or not the waste contains' the predominantly gamma-emitting nuclides. (typically, Co-60 or Cs-137/Ba-137)._. However, the -
i classification of most cartridge filters is more'likely to be controlled by-C" or transuranic concentrations.
In determining the class'ification of a l
container of filters, one or more of the following paragraphs may apply.
i-1 Averacina involvina nredominant a m -emitters For the purpose of classifying multiple cartridge filters containing Co-60 or l
l Cs-137/Ba-137, their individual nuclide concentrations may be based on the~
volumetric-averaged concentration of the combined filters, provided that the j
]
concentrations within the individual filters in the disposal container or'
{
liner are within a factor of 1.5 of the respective. averaged concentration values of each nuclide. This factor of 1.5.does not apply if the classification of. the combined-filters, as a result of other nuclides, is higher than the class derived from the predominantly ganna-emitter concentrations.
h 4
9 16-
1 Avernaina involvino radionuclides other than crimary a- -emitters For the purpose of classifying multiple cartridge filters, the concentrations of all 661.55 tabulated radionuclides in the disposal container or liner, other than Co-60, Nb-94, and Cs-137/Ba-137, may be based on the volumetric-or weight-averaged concentrations of the combined materials.
In this case, all the concentrations of the " classification-controlling" individual nuclides within all the individual filters should be within a factor of 10 of their respective averages over all items in the mixture.
Mixtures containina multiple radionuclides-l For cartridge filters containing combinations of tabulated nuclides, the sum-of-the-fractions rule described in 661.55(a)(7) would apply.
For cartridge
)
filters, this rule would typically involve suming the fractions of the appropriate 561.55 Table 1 or Table 2 concentration values of the nuclides j
other than the predominantly gamma-emitters. The respective fractions
-I contributing to the sua can be calculated by using the " highest concentration" associated with any filter or, if applicable, the concentration determined by using the " averaging" methods described previously.
Independent of whether the " highest concentration" or " averaging" method is
]
used to classify multiple filters in a disposa1, container / liner, in accordance with Section III of Appendix F to 10 CFR Part 20, the licensee classifying the mixture of filters must have in place a quality control program to ensure com-pliance with the waste classification provisions of 561.55. As part of this j
quality control program, if the classification of the mixture of filters is 4
based on the volumetric-or weight-averaged nuclide concentrations of the dis-posal container / liner contents, as allowed above, the licensee responsible for 1
classification of the waste should prepare, retain with manifest documenta-tion, and have available for inspection, a record documenting the licensee's waste classification analyses. This record or analysis should be sufficient 1
l to show that the averaging.of concentrations over all the contents in the dis-posal container / liner was not undertaken solely to lower.the classification of any specific cartridge in the disposal container / liner.
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Examole: A liner contains 4 cartridge filters. Note:
In actual cases, more than this number could be contained in a liner. The filter volumes, weights and principal " classification-controlling" nuclide activities are shown below along with the nuclides' concentration expressed as a fraction (frac) of-appropriate Table 1 concentration values. A Cs-137 concentration is also -
l presented.
Fuel Pool Fuel Pool.
Reactor Coolant Reactor Coolant I
Filter #1-Filter #2 Filter #1 Filter #2.
Volume (f})3) 0.85 0.85' O.45-0.45 (m
0.024 0.024 0.0127 0.0127 1
Weight (1bs) 20 20 9
9 j
(kg) 9.08 9.08 4.09 4.09 i
Nuclide fj fr.E;.
Si ffE G1-InG
.CJ.
ffE C-14 0.01 0.01 0.52 0.009 0.047 0.005 0.05 0.002 0.02 Pu-241 0.008
-0.25 0.007 0.22 0.01 0.71 0.004 0.28.
TRU 0.0004 0.44 0.0003' O.33 0.0005 1.24 0.0002 0.49' i
Table 1 Total-0.74 0.60 2.00 0.79 concentration concentration concentration concentration 3
Cs-137 1.5 x 10 Ci/m 1 x 10 C1/m*
1 x 10". C1/m' 4 x 10 Ci/m' The Cs-137/Ba-137 activity in all the filters is sufficiently small such that; the classification of the filters will not be determined by this gamma-emitting nuclide.
Similarly, other nuclides to which Tab 1'e 2 values may apply have not been listed since their values will not affect cartridge. filter clas-sification. Thus, the four filters listed could be placed in a single dis-posal container / liner since all the listed nuclide concentrations are within an order of magnitude of the. averaged concentrations. The sum-of-the-1 fractions for the three nuclides would be: C-14, (0.04) + Pu-241, (0.32) +
TRU, (0.53) = 0.89, indicating that the multiple, filters could be classified as Class C waste.
Epste in hiah-intearity containers In the case of cartridge filters' stabilized by emplacement within high!
integrity containers, the volume or weight used to determine waste classifica-tion should be calculated over the displaced volume (interstitial space within the filters may be included) or weight of the cartridge filter itself rather 18
1
(
than the gross volume or weight of the container.
Similarly, the volume and l
mass considered for purposes of waste classification of dewatered ion-exchange resins, filter backwashes, and filter media placed into high integrity con-tainers should be the volume and mass of the contained waste.
In both these cases, disposal in a high integrity container is not considered to alter the as-buried concentrations of radioactivity.
Encaosulation of solid material For routine wastes such as filters, filter cartridges, or sealed sources centered in an encapsulated mass, classification may be based on the overall volume of the final solidified mass, provided that:
(1) the volume and attri-l butes of the encapsulated waste comply with the constraints established in l
Appendix C in this [ expansion of the] Technical Position; (2) the solidified mass meets the waste form structural stability criteria of 561.56 for Class B and Class C waste; and (3) the disposal unit containing the encapsulated mass is segregated from disposal units containing class A wastes which do not meet:
l the structural stability requirements in 5561.56(b). Under the above provi-sions, additional protection is provided through the shielding, lack of dis-persibility, or identifiability of the encapsulated mass; and, for Class C encapsulated waste, by the land disposal facility operational requirements in 5561.52(a)(2). This additional protection has been considered in the classi-fication position developed in Appendix C and has been balanced against the hypothetical radiological impact caused by potential interactions between assumed intruders and the encapsulated mass.
Mixina of dissimilar waste streams (different waste tvoes)
Classifications may also be needed in situations involving a mixture of miscellaneous waste materials -- e.g., situations in which contaminated l
valves, piping, or similar components are placed in containers mixed with other trash; or miscellaneous trash or components are mixed with other radio-active materials such as resins or filters.
In such cases, because of poten-tial differences in waste interactions with the disposal environment, waste classification involving averaging the total activity over the total volume or mass of the waste in the container would be accepted if the classification of the mixture is not lower than the highest waste classification of any 19
individual components of the mixture. This provision does not apply to small concentrated microcurie sources (<3.7 MBq (100 C1)) of waste such as check sources or gauges which may be mixed with contaminated trash waste streams.
The activity of such check sources or gauges may be averaged over the trash volume. Other classification practices may be determined to be acceptable under the " Alternative provisions" paragraph which follows.
Alternative orovisions Under 561.58, the Commission, upon request, may authorize other provisions for the classification and characteristics of waste on a specific basis if, after evaluation of the specific characteristics of the waste, disposal site and j
method of disposal, it finds reasonable assurance of compliance with the performance objectives in Subpart C of 10 CFR Part 61.
Alternatives to the determination of radionuclide concentrations for waste classification purposes, other than those defined in this technical position',
j may be considered acceptable. For example, the physical form of certain discrete wastes (e.g., activated metals) may be such that intruder exposure scenarios, other thr.: those used to establish the values in Tables I and 2 of l
661.55, may be appropriate. A case in point could be the di'sposal of a large intact activated component filled with a structurally stable medium (e.g.,
cement) or enclosed in a massive robust container capable of meeting f
structural stability requirements. A request that demonstrates with reasonable assurance that the performance objectives in Subpart C of 10 CFR Part 61 are met may be used to justify that the waste is acceptable for near-surface disposal. Alternatives would require the approval of, or otherwise be authorized by, the NRC or Agreement State regulatory agency.
In some cases (e.g., if the approaches in this technical position had been incorporated as disposal facility license conditions), the disposal facility may need to apply for a license amendment from the NRC or Agreement State regulatory agency to incorporate the alternative provision in its license.
Table C provides a summary of the primary aspects of the tbove guidance.
20
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-Table C Volumes and Masses for Determination *of Concentration i
1 J
Waste Tvos Allowable Classification Volume or Mass l
Contaminated trash or soil Reasonable fill volume of container / mass
)
of waste (<10( void)*
Absorbed liquids Volume / mass of liquid prior to l
absorption j
j Solidified liquids Volume / mass of solidified mass j
Solidified ion-exchange resins Volume / mass of solidified mass *'
j Dewatered ion-exchange resins in Displaced (bulk) ' olume (interstitial v
i high integrity containers or volume may be included)/dewatered j
liners mas:. ef ion-exchange resins j
Filter cartridges in~high integrity Disriaced volume (interstitial volume containers or liners may be included)/ mass'of filters *-
}
Activated components, components Full density volume /(major void volumes f
containing radioactivity in subtracted from envelnpa volume)/
their design, or' contaminated mass of componentst materials Encapsulated ' filter cartridges Volume / mass of solidified mass when j
or sealed sources encapsulated in accordance with the j
guidance provided~in Appendix C in this expansion of the Technical l
Position i
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- If homogeneity maintained in solidified mass j
- Mixtures of waste streams subject to additional guidance defined in text.
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APPENDIX C l
POSITION ON ENCAPSULATION OF SEALED SOURCES AND OTHER l
SOLID LOW-LEVEL RADIOACTIVE WASTES t
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l Encapsulation can mitigate dispersion of waste and can also provide additional-i shielding to limit external radiation fields.
If provided to meet the stabil-ity criteria of 561.56(b) and coupled with the technical requirements ~ for land disposal facilities in subpart_D of 10 CFR Part 61 (specifically, 961.52),
encapsulation will limit the' impacts from both (1) the direct exposure, j
inhalation, and ingestion pathways associated with potential intruder-waste interactions and (2) the potential exposure pathways to individual members of i
l the public involving groundwater and agricultural products.
t l
The amount of credit allowed for encapsulation, though, needs to be limited so 1
that -extreme measures cannot be taken solely for the purposes of dilution. To be consistent with the NRC's policy on volume reduction and to limit extremely e
large " point sources" of radioactivity in the disposal site, generally
]
acceptable values for minimum and maximum encapsulated waste volumes and j
masses, nuclide activities and radiation levels are established.
I These general.ly acceptable bounding conditions are as follows:
(1) A minimum solidified volume or mass for encapsulation should be that i
which can reasonably be expected to increase the difficulty of an inadver-i tent intruder moving the waste by hand following the' loss of institu-tional control over the disposal site. This minimum size or weight j-should preclude any significant movement without the' assistance of 2
mechanical equipment.
i (2) A maximum solidified volume or mass for encapsulation (from which
'j l
concentrations are determined)_should be 0.2m3 or 500Kg (typical 55-i gallon drum).
Larger volumes and masses may be used for encapsulation i
but, in general, unless a specific rationale -is 'provided, no credit
[
beyond the volume or mass indicated should be considered when determining waste concentrations.
j Note: The bounding volumes and weights in (1) and (2) will ensure that the potential radiological impacts from encapsulated-discrete source dis-posals are within the envelope of impacts which would be calculated if the radioactivity was homogeneously distributed throughout the encapsulating media.
i 3-(3) A maximum amount of gamma-emitting radioactivity (e.g., Cs-137/Ba-137 Nb-94) or radioactive material generally acceptable for encapsulation is i
that which, if credit is taken for a 500-year decay period, would result-in a dose rate of less than 0.2pSv/hr (0.02mres/hr) on the surface of. the i
encapsulating media (refer to footnote 1, following page). The calcu-lation to determine compliance with this criterion may consider the (minimum attenuation factor provided by the shielding properties of the 22 l
i 1
j i
encapsulating media but, in general, this factor should not exceed an i
attenuation factor that would be provided by 15 inches of concrete j
encapsulating material (refer to footnote 2).. Furthermore, the maximum Cs-137/Ba-137 gauna-emitting generally acceptable for encapsulation in a single disposal container is 1.1 TBq (30 curies) (refer to footnote 3).
)
(4) A maximum amount of any radionuclide that should be. encapsulated in a i
single disposal container intended for disposal at a commercial LLW dis-1 posal. facility is that~ which, when averaged over the waste and the encap-sulating media,.does not exceed the maximum concentration limits for Class C waste as defined in Tables 1 and 2 of $61.55 (refer to footnote 4, following page).
(5) In all cases when a discrete source of radioactive solid waste is encap-j sulated, written procedures should be established to ensure that the-radiation source (s) is reasonably centered within the encapsulating i
media.
l.
Footnotes i
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l' Presuming the inadvertent intruder has contact with the encapsulated
)
3 waste as generally defined in the intruder-agricultural. scenario (refer-ence NUREG-0945), this dose rate would. result in an annual exposure of
)
j less than 1/10 of that which would be received if the radioactivity was =
i homogenized over a soil volume equivalent to the encapsulating media.
j This factor of 10 takes into consideration the possibility that the intruder may be exposed to both (1) other encapsulated waste whir.h may be j
excavated from the disposal trenches without mixing with uncontaminated cover material and (2) other homogenized waste.
2 The 15 inches of concrete shielding is that necessary to ensure that an encapsulated 30 Ci source of Cs-137/Ba-137. could satisfy the 0.2pSv/hr (0.02 ares /hr) dose criteria. Additional shielding thicknesses from the i
encapsulating or disposal unit materials could be expected to be in existence after 500 years,.but because of uncertainties regarding shielding orientations and effectiveness following this time period, no j
greater credit is considered generally appropriate. Furthermore, absent any shielding, intruder doses would still be expected to be similar.to doses which would'be received from homogeneous waste at concentrations permitted in 161.55.
3 The 30-curie value for Cs-137/Ba-137 results from the ' application of the j
dose rate and shielding criteria.in bounding condition 3..
j 4
Reasserting the applicability of Tables 1 and 2 of 161.55 emphasizes j
j that, for alpha-or beta-emitting radionuclides, encapsulation under i
bounding conditions 1 through 3 does agi provide an exemption to the classification tables in the regulations. As a result, the largest activity of a transuranic nuclide, other than Pu-241.and Cm-242, that is generally acceptable for e'ncapsulation in 0.2m3 is;about1.1GBq.(30mC1),
_q presuming the density of the encapsulating mass is 1.3 g/cm3 For~
i determining mass-based concentrations, it is generally acceptable to take
- credit for the actual density of the material if the density is less than j
3 2.5/cm.
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n ANALYSIS OF AND RESPONSE TO ColeENTS ON
" CONCENTRATION AVERAGING AND ENCAPSULATION TECHNICAL POSITION" On June 20, 1992, the Nuclear Regulatory Comission noticed in the Federal Register the availability of a proposed technical position on concentration averaging and encapsulation for low-level radioactive waste intended for land facility disposal. The proposed position would expand upon and revise, in part, the Technical Position on Radioactive Waste Classification which was issued in May 1983. Coments on the proposed position were solicited and, in response,19 coment letters were received, i
These responses included eleven from nuclear utilities and one from their association, the Edison Electric Institute. Both disposal facility operators 4
responded as did the Department of Energy (twice), the Department of the Navy, a firm active in the waste classification field, and a State regulatory agency. These letters raised the following major issues:
(1) the position, as a whole, significantly modifies the process and intent of NRC's regulations as defined in 10 CFR Part 61 and, as such, has not been sufficiently justified; (2) the position does not go far enough in defining whether certain existing
" averaging" practices are acceptable; (3) the approach taken to classify waste containing gama-emitting nucli. des listed in the tables of $61.55 is overly consen Vative; (4) the position will drive wastes (e.g., activated metals, cartridge filters) to higher classifications resulting in increased costs without any comensurate benefit; and (5) the major approaches defined in the position should be incorporated into NRC's 10 CFR Part 61 regulations.
In responding to some of these coments (e.g., (2) and (4)), the proposed technical position has been significantly expanded. A sumary description of j
the expanded position, as well as NRC's responses to the other major coments are provided below:
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1.
Position Justification l
l In the environmental impact statement (EIS) supporting the promulgation-of 10 CFR Part 61, the concentration values that appear in Tables 1 and 2 of 561.55 l
were based on potential exposures to inadvertent intruders. The intruder dose j
calculations included a scenario-which presumed that the waste is exhumed from its disposed location and spread over the land surface. The waste was assumed l
to be indistinguishable from soil and, as such, factors accounting for mixing-
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[
of the contaminated soil with clean interstitial and cover material were l
l included in the dose projections. The basis for this revision to the 1983 j
Technical Position recognizes this. fact and, in'large part, has attempted to
]
i define " concentration averaging and encapsulation" positions for the disposal.
of discrete wastes or mixtures of such wastes that will fall within the'
" envelope of safety" defined in the EIS. Thus, the position reflects the possibility that an intruder may be exposed to-discrete wastes with localize'd concentrations of radionuclides that can be larger than in the exhumed-contaminated soil assumed in the EIS. As a result, the position defines a i
subset of what would constitute acceptable practices for characterizing either the volumes or masses of specific wastes that should be used for waste classification purposes. To establish what constitutes an " acceptable practice" for meeting the performance objectives at 161.42, the position considers exposure scenarios that are more likely to apply to intruder interactions with discrete waste than with waste that is indistinguishable j
from soil (e.g., handling scenarios). These exposure scenarios underlie the i
e revised technical position and lead, for example, to the differing approaches for defining acceptable concentration averaging or encapsulation positions based on the predominant type of radiation incorporated in the waste.
With regard to the treatment accorded to mixtures of " homogeneous" wastes,'the position reflects'the fact that specific volumes af Class A, B and C wastes were' defined in the EIS analyses. Thus, while.it is theoretically true that homogeneous Class B and C wastes could be diluted with less concentrated waste 4
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so as to eventually qualify a mixture as Class A waste, this was not the general rationale behind the Part 61 regulation.
Instead of allowing
.i unlimited dilution or mixing, the regulation imposes waste st' ability requirements at 161.56, and, for Class C waste, additional measures to be taken at the disposal facility to protect against inadvertent intrusion'[see il61.55(a)(2)(iii) and 61.7(b)(5)].
i Under the above rationales, a number of reasonable concentration averaging / encapsulation positions could be developed and justified. Since it was recognized that Agreement States will play'a major role in the licensing _
and regulation of disposal facilities and that, as a result, there was a need
~
to foster, to the gre'atest extent possible, the use of uniform guidance, the proposed position was formulated in cooperation with the E-S Committee on Radioactive Waste Management of the Conference of Radiation Control Program l
Directors (CRCPD). Thus, the original proposed position provided guidance'on t
concentration averaging and encapsulation practices that were likely to be generally accepted.
It was the intent that~ the classification or encapsulation of. a specific waste not generally addressed in the position could be deemed acceptable under the " Alternative provisions" paragraph of i
section C.3.
This concept has now been emphasized and has been specifically state'd at an early point in the position and, as the response to issue 2 indicates, the position has been further expanded to define other specific 1
practices which would be considered acceptable.
i 2.
Position Exoansion to Address Current Practices Most commenters stated that, notwithstanding the " Alternative provisions" paragraph, the position should specifically. address the acceptability of certain current practices.. In particular, these commenters highlighted the need for a further definition of acceptable " concentration-determination or averaging" practices as applied to resins, activated metals, contaminated a
materials, cartridge filters and, where applicable, to the classification of waste items which may be " sectioned" or " cut up" for operational reasons.
1 In response, the position has been significantly expanded. As a result, the j
following specific practices are addressed:
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(a) single-point collection of resins from different systems within a 1
facility which occur. as a result.of reasonable design or operational-
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practices is not considered " mixing";
j (b) criteria have been added for determining whether sectioned pieces
]
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should be considered as individual items for classification purposes; (c) a small range of concentration differences between individual items j
containing or contaminated with the predominantly gamma-emitting j
nuclides (Co-60, Nb-94, and Cs-137) has been specified over which j
concentration averaging can take place, and averaging is always l
permitted for the specific gamma-emitting nuclide if its activity within l
or on an item or component is less than 37 MBq (1 mci).
j 1
j Items (b) and (c) above have added a significant amount of detail to the position which has, in turn, necessitated the further addition of example-1 i
cases and a logic diagram figure for the classification of activated metals.
j f.
l 3.
Treatment of G-- -Emittina Wastes j
Absent the explanation provided in issue 1, most connenters stated that the j
approach taken to classify waste which contains the predominantly gamma-emitting nuclides listed in Tables 1 and 2 of 161.55 is overly conservative.
2 J
1 L
Given the distinction between " discrete waste" and'" waste indistinguishable l
from. soil", and the regulatory significance of' intruder exposures, the NRC j
staff continues to believe that a distinction between gamma-and alpha-or beta-containing waste can and should be made within the context of the Part 61 regulations (see response to issue 5). However,-the staff believes that
{.
some limited flexibility should be provided in' the averaging of a mixture of such wastes'and that further explicit guidance on the acceptability of j
specific practices is necessary. The technical position has therefore been revised to allow concentration averaging between items containing or contaminated with the predominantly gamma-emitting nuclides, if the j
concentrations within the individual items are within a factor of 1.5 of the J.
averaged individual nuclide concentrations. The averaged concentration value within a disposal container would be used to determine waste classification as i
described in 561.55. Under this constraint, a practical degree of flexibility I
is achieved in cases where components may contain 561.55 tabulated nuclides
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9 with concentrations near the " classification table breakpoints." Since the averaged values would still be compared with 561.55 values, this small degree j
of flexibility is not considered to compromise the objectives of the I
classification system in protecting the inadvertent intruder and will minimize occupational exposures associated with unnecessary waste segregation. Under the proposed constraint, the protection provided to the potential intruder would also be well-within the envelope of safety being provided through the -
encapsulated source position. Averaging of a specific gamma-emitting nuclide is also permitted if contained within or on an item or component in a quantity less than 37 MBq (1 mci).
As far as more explicit guidance is concerned, the position has been revised to include criteria for determining when " sectioned" or " cut up" pieces of larger components should be considered as separate items for classification purposes. The criteria involve the volume,- weight, and activity.of the individual pieces, as well as conditions involving the disposition of the pieces with regard to the whole (i.e., whether all pieces are placed in the same disposal container).
4.
Imoact on Current Disoosals i
)
Several commenters believed two aspects of the proposed position would cause significant increase in' waste samplings and associated papemork:
(1) the separate consideration of the predominantly gamma-and non-gamma-emitting nuclides in determining concentrations for waste classification purposes, and (2) the approach taken with regard to classification _of activated or contami-nated components which need to be " sectioned" or " cut-up" for operational considerations. These commenters also generally believed that the proposed position would cause both an increase in the amount of LLW and an overall shift toward higher classifications.
The intent of the proposed technical position was not only to_ provide gener-I ally acceptable concentration-averaging and encapsulation guidance but to also-include a procedure through which other ' acceptable positions could be pro-posed, reviewed by appropriate regulating authorities, and, if approved, documented in a disposal facility's license conditions. This latter procedure was described in the " Alternative provisions" paragraph of the proposed 5
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technical position. Through this procedure, it was expected that most, if not
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all, current practices would be justified and approved; thus, significant i
increases in samplings and paperwork, and shifts to higher waste classifica-tions were not anticipated. However, the NRC staff agrees, as indicated in i
the issue 2 discussion, that a reasonable attempt to address the universe of useful concentration-averaging and encapsulation practices (specifically, j
current practices) should be.made. As.a result, the position has been l
expanded not only to further address acceptable current practices but to provide explanatory logic diagrams and supporting examples. The. staff.'still believes, however, that the " Alternative positions" section is a significant feature of the position since a number of decisions involving concentration-averaging or encapsulation will need to be made on a case-by-case basis.
4 5.
Need to Incornorate Position 'into Reaulatisns l
Several commenters stated their belief that the proposed position was a significant departure from the conclusions of the Environmental Impact l
Statement for 10 CFR Part 61, and, as such, should be' promulgated through the rulemaking process. The staff notes that the 10 CFR Part 61 regulations at fl61.55(a)(8) state that for determining concentrations in waste, "The concentration of a radionuclide may be averaged over the volume of the waste, or weight of the waste..."
The staff believes that the regulations provide considerable flexibility in defining the volumes or masses of waste that are appropriate for classification purposes.
For example, the EIS recognized the i
need to set out classification'11mits for all wastes, and.then consider potential allowances for particular waste streams. The EIS also recognized that the applicability of the intruder-discovery or -agricultural scenarios could be dependent on case-by-case evaluation of specific waste foms. The NRC staff believes that the position provides guidance which is based on these factors and is entirely consistent with 10 CFR 61. Therefore, a rulemaking on the subject is not'necessary.
Furthermore, the position has been clarified to point out that the concentration averaging and encapsulation _ guidance
~
represents-only a subset of practices which could be judged to be potentially acceptable. These further practices may be approved as described in the
" Alternative provisions" paragraph.
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