[Code of Federal Regulations]
[Title 40, Volume 24]
[Revised as of July 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR191.27]
[Page 13-17]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 191_ENVIRONMENTAL RADIATION PROTECTION STANDARDS FOR MANAGEMENT AND
DISPOSAL OF SPENT NUCLEAR FUEL, HIGH-LEVEL AND TRANSURANIC RADIOACTIVE
WASTES--Table of Contents
Subpart C_Environmental Standards for Ground-Water Protection
Sec. 191.27 Effective date.
The standards in this subpart shall be effective on January 19,
1994.
Appendix A to Part 191--Table for Subpart B
Table 1--Release Limits for Containment Requirements
[Cumulative releases to the accessible environment for 10,000 years
after disposal]
------------------------------------------------------------------------
Release
limit per
1,000
MTHM or
other
Radionuclide unit of
waste
(see
notes)
(curies)
------------------------------------------------------------------------
Americium-241 or -243........................................ 100
Carbon-14.................................................... 100
Cesium-135 or -137........................................... 1,000
Iodine-129................................................... 100
Neptunium-237................................................ 100
Plutonium-238, -239, -240, or -242........................... 100
Radium-226................................................... 100
Strontium-90................................................. 1,000
Technetium-99................................................ 10,000
Thorium-230 or -232.......................................... 10
Tin-126...................................................... 1,000
Uranium-233, -234, -235, -236, or -238....................... 100
Any other alpha-emitting radionuclide with a half-life 100
greater than 20 years.......................................
Any other radionuclide with a half-life greater than 20 years 1,000
that does not emit alpha particles..........................
------------------------------------------------------------------------
Application of Table 1
Note 1: Units of Waste. The Release Limits in Table 1 apply to the
amount of wastes in any one of the following:
(a) An amount of spent nuclear fuel containing 1,000 metric tons of
heavy metal (MTHM) exposed to a burnup between 25,000 megawatt-days per
metric ton of heavy metal (MWd/MTHM) and 40,000 MWd/MTHM;
(b) The high-level radioactive wastes generated from reprocessing
each 1,000 MTHM exposed to a burnup between 25,000 MWd/MTHM and 40,000
MWd/MTHM;
(c) Each 100,000,000 curies of gamma or beta-emitting radionuclides
with half-lives greater than 20 years but less than 100 years (for use
as discussed in Note 5 or with materials that are identified by the
Commission as high-level radioactive waste in accordance with part B of
the definition of high-level waste in the NWPA);
(d) Each 1,000,000 curies of other radionuclides (i.e., gamma or
beta-emitters with half-lives greater than 100 years or any alpha-
emitters with half-lives greater than 20 years) (for use as discussed in
Note 5 or with materials that are identified by the Commission as high-
level radioactive waste in accordance with part B of the definition of
high-level waste in the NWPA); or
[[Page 14]]
(e) An amount of transuranic (TRU) wastes containing one million
curies of alpha-emitting transuranic radionuclides with half-lives
greater than 20 years.
Note 2: Release Limits for Specific Disposal Systems. To develop
Release Limits for a particular disposal system, the quantities in Table
1 shall be adjusted for the amount of waste included in the disposal
system compared to the various units of waste defined in Note 1. For
example:
(a) If a particular disposal system contained the high-level wastes
from 50,000 MTHM, the Release Limits for that system would be the
quantities in Table 1 multiplied by 50 (50,000 MTHM divided by 1,000
MTHM).
(b) If a particular disposal system contained three million curies
of alpha-emitting transuranic wastes, the Release Limits for that system
would be the quantities in Table 1 multiplied by three (three million
curies divided by one million curies).
(c) If a particular disposal system contained both the high-level
wastes from 50,000 MTHM and 5 million curies of alpha-emitting
transuranic wastes, the Release Limits for that system would be the
quantities in Table 1 multiplied by 55:
[GRAPHIC] [TIFF OMITTED] TC11NO91.000
Note 3: Adjustments for Reactor Fuels with Different Burnup. For
disposal systems containing reactor fuels (or the high-level wastes from
reactor fuels) exposed to an average burnup of less than 25,000 MWd/MTHM
or greater than 40,000 MWd/MTHM, the units of waste defined in (a) and
(b) of Note 1 shall be adjusted. The unit shall be multiplied by the
ratio of 30,000 MWd/MTHM divided by the fuel's actual average burnup,
except that a value of 5,000 MWd/MTHM may be used when the average fuel
burnup is below 5,000 MWd/MTHM and a value of 100,000 MWd/MTHM shall be
used when the average fuel burnup is above 100,000 MWd/MTHM. This
adjusted unit of waste shall then be used in determining the Release
Limits for the disposal system.
For example, if a particular disposal system contained only high-
level wastes with an average burnup of 3,000 MWd/MTHM, the unit of waste
for that disposal system would be:
[GRAPHIC] [TIFF OMITTED] TC11NO91.001
If that disposal system contained the high-level wastes from 60,000
MTHM (with an average burnup of 3,000 MWd/MTHM), then the Release Limits
for that system would be the quantities in Table 1 multiplied by ten:
[GRAPHIC] [TIFF OMITTED] TC11NO91.002
which is the same as:
[GRAPHIC] [TIFF OMITTED] TC11NO91.003
Note 4: Treatment of Fractionated High-Level Wastes. In some cases,
a high-level waste stream from reprocessing spent nuclear fuel may have
been (or will be) separated into two or more high-level waste components
destined for different disposal systems. In such cases, the implementing
agency may allocate the Release Limit multiplier (based upon the
original MTHM and the average fuel burnup of the high-level waste
stream) among the various disposal systems as it chooses, provided that
the total Release Limit multiplier used for that waste stream at all of
its disposal systems may not exceed the Release Limit multiplier that
would be used if the entire waste stream were disposed of in one
disposal system.
Note 5: Treatment of Wastes with Poorly Known Burnups or Original
MTHM. In some cases, the records associated with particular high-level
waste streams may not be adequate to accurately determine the original
metric tons of heavy metal in the reactor fuel that created the waste,
or to determine the average burnup that the fuel was exposed to. If the
uncertainties are such that the original amount of heavy metal or the
average fuel burnup for particular high-level waste streams cannot be
quantified, the units of waste derived from (a) and (b) of Note 1 shall
no longer be used. Instead, the units of waste defined in (c) and (d) of
Note 1 shall be used for such high-level waste streams. If the
uncertainties in such information allow a range of values to be
associated with the original amount of heavy metal or the average fuel
burnup, then the calculations described in previous Notes will be
conducted using the values that result in the smallest Release Limits,
except that the Release Limits need not be smaller than those that would
be calculated using the units of waste defined in (c) and (d) of Note 1.
Note 6: Uses of Release Limits to Determine Compliance with Sec.
191.13 Once release limits for a particular disposal system have been
determined in accordance with Notes 1 through 5, these release limits
shall be used to determine compliance with the requirements of Sec.
191.13 as follows. In cases where a mixture of radionuclides is
projected to be released to the accessible environment, the limiting
values shall be determined as follows: For each radionuclide in the
mixture, determine the ratio between the cumulative release quantity
projected over 10,000 years
[[Page 15]]
and the limit for that radionuclide as determined from Table 1 and Notes
1 through 5. The sum of such ratios for all the radionuclides in the
mixture may not exceed one with regard to Sec. 191.13(a)(1) and may not
exceed ten with regard to Sec. 191.13(a)(2).
For example, if radionuclides A, B, and C are projected to be
released in amounts Qa, Qb, and Qc, and
if the applicable Release Limits are RLa, RLb, and
RLc, then the cumulative releases over 10,000 years shall be
limited so that the following relationship exists:
[GRAPHIC] [TIFF OMITTED] TC11NO91.004
[50 FR 38084, Sept. 19, 1985, as amended at 58 FR 66415, Dec. 20, 1993]
Appendix B to Part 191--Calculation of Annual Committed Effective Dose
I. Equivalent Dose
The calculation of the committed effective dose (CED) begins with
the determination of the equivalent dose, HT, to a tissue or
organ, T, listed in Table B.2 below by using the equation:
[GRAPHIC] [TIFF OMITTED] TR20DE93.009
where DT, R is the absorbed dose in rads (one gray, an SI
unit, equals 100 rads) averaged over the tissue or organ, T, due to
radiation type, R, and wR is the radiation weighting factor
which is given in Table B.1 below. The unit of equivalent dose is the
rem (sievert, in SI units).
Table B.1--Radiation Weighting Factors, wR\1\
------------------------------------------------------------------------
wR
Radiation type and energy range \2\ value
------------------------------------------------------------------------
Photons, all energies........................................... 1
Electrons and muons, all energies............................... 1
Neutrons, energy < 10 keV....................................... 5
10 keV to 100 keV..................................... 10
100 keV to 2 MeV........................... 20
2 MeV to 20 MeV............................ 10
20 MeV..................................... 5
Protons, other than recoil protons, 2 MeV............ 5
Alpha particles, fission fragments, heavy nuclei................ 20
------------------------------------------------------------------------
\1\ All values relate to the radiation incident on the body or, for
internal sources, emitted from the source.
\2\ See paragraph A14 in ICRP Publication 60 for the choice of values
for other radiation types and energies not in the table.
II. Effective Dose
The next step is the calculation of the effective dose, E. The
probability of occurrence of a stochastic effect in a tissue or organ is
assumed to be proportional to the equivalent dose in the tissue or
organ. The constant of proportionality differs for the various tissues
of the body, but in assessing health detriment the total risk is
required. This is taken into account using the tissue weighting factors,
wT in Table B.2, which represent the proportion of the
stochastic risk resulting from irradiation of the tissue or organ to the
total risk when the whole body is irradiated uniformly and HT
is the equivalent dose in the tissue or organ, T, in the equation:
[GRAPHIC] [TIFF OMITTED] TR20DE93.010
Table B.2--Tissue Weighting Factors, wT \1\
------------------------------------------------------------------------
Tissue or organ wT value
------------------------------------------------------------------------
Gonads.................................................. 0.25
Breast.................................................. 0.15
Red bone marrow......................................... 0.12
Lung.................................................... 0.12
Thyroid................................................. 0.03
Bone surfaces........................................... 0.03
Remainder............................................... \2\ 0.30
------------------------------------------------------------------------
\1\ The values are considered to be appropriate for protection for
individuals of both sexes and all ages.
\2\ For purposes of calculation, the remainder is comprised of the five
tissues or organs not specifically listed in Table B.2 that receive
the highest dose equivalents; a weighting factor of 0.06 is applied to
each of them, including the various sections of the gastrointestinal
tract which are treated as separate organs. This covers all tissues
and organs except the hands and forearms, the feet and ankles, the
skin and the lens of the eye. The excepted tissues and organs should
be excluded from the computation of HE.
III. Annual Committed Tissue or Organ Equivalent Dose
For internal irradiation from incorporated radionuclides, the total
absorbed dose will be spread out in time, being gradually delivered as
the radionuclide decays. The time distribution of the absorbed dose rate
will vary with the radionuclide, its form, the mode of intake and the
tissue within which it is incorporated. To take account of this
distribution the quantity committed equivalent dose, H[Tau]([tau]) where
is the integration time in years following an intake over any particular
year, is used and is the integral over time of the equivalent dose rate
in a particular tissue or organ that will be received by an individual
following an intake of radioactive material into the body. The time
period, [tau], is taken as 50 years as an average time of exposure
following intake:
[GRAPHIC] [TIFF OMITTED] TR20DE93.011
for a single intake of activity at time t0 where
HT(t) is the relevant equivalent-dose rate in a tissue or
organ at time t. For the purposes of this part, the previously mentioned
single intake may be considered to be an annual intake.
[[Page 16]]
IV. Annual Committed Effective Dose
If the committed equivalent doses to the individual tissues or
organs resulting from an annual intake are multiplied by the appropriate
weighting factors, wT, and then summed, the result will be
the annual committed effective dose, E([tau]):
[GRAPHIC] [TIFF OMITTED] TR20DE93.012
[58 FR 66415, Dec. 20, 1993]
Appendix C to Part 191--Guidance for Implementation of Subpart B
[Note: The supplemental information in this appendix is not an
integral part of 40 CFR part 191. Therefore, the implementing agencies
are not bound to follow this guidance. However, it is included because
it describes the Agency's assumptions regarding the implementation of
subpart B. This appendix will appear in the Code of Federal
Regulations.]
The Agency believes that the implementing agencies must determine
compliance with Sec. Sec. 191.13, 191.15, and 191.16 of subpart B by
evaluating long-term predictions of disposal system performance.
Determining compliance with Sec. 191.13 will also involve predicting
the likelihood of events and processes that may disturb the disposal
system. In making these various predictions, it will be appropriate for
the implementing agencies to make use of rather complex computational
models, analytical theories, and prevalent expert judgment relevant to
the numerical predictions. Substantial uncertainties are likely to be
encountered in making these predictions. In fact, sole reliance on these
numerical predictions to determine compliance may not be appropriate;
the implementing agencies may choose to supplement such predictions with
qualitative judgments as well. Because the procedures for determining
compliance with subpart B have not been formulated and tested yet, this
appendix to the rule indicates the Agency's assumptions regarding
certain issues that may arise when implementing Sec. Sec. 191.13,
191.15, and 191.16. Most of this guidance applies to any type of
disposal system for the wastes covered by this rule. However, several
sections apply only to disposal in mined geologic repositories and would
be inappropriate for other types of disposal systems.
Consideration of Total Disposal System. When predicting disposal
system performance, the Agency assumes that reasonable projections of
the protection expected from all of the engineered and natural barriers
of a disposal system will be considered. Portions of the disposal system
should not be disregarded, even if projected performance is uncertain,
except for portions of the system that make negligible contributions to
the overall isolation provided by the disposal system.
Scope of Performance Assessments. Section 191.13 requires the
implementing agencies to evaluate compliance through performance
assessments as defined in Sec. 191.12(q). The Agency assumes that such
performance assessments need not consider categories of events or
processes that are estimated to have less than one chance in 10,000 of
occurring over 10,000 years. Furthermore, the performance assessments
need not evaluate in detail the releases from all events and processes
estimated to have a greater likelihood of occurrence. Some of these
events and processes may be omitted from the performance assessments if
there is a reasonable expectation that the remaining probability
distribution of cumulative releases would not be significantly changed
by such omissions.
Compliance with Sec. 191.13. The Agency assumes that, whenever
practicable, the implementing agency will assemble all of the results of
the performance assessments to determine compliance with Sec. 191.13
into a ``complementary cumulative distribution function'' that indicates
the probability of exceeding various levels of cumulative release. When
the uncertainties in parameters are considered in a performance
assessment, the effects of the uncertainties considered can be
incorporated into a single such distribution function for each disposal
system considered. The Agency assumes that a disposal system can be
considered to be in compliance with Sec. 191.13 if this single
distribution function meets the requirements of Sec. 191.13(a).
Compliance with Sec. Sec. 191.15 and 191.16. When the uncertainties
in undisturbed performance of a disposal system are considered, the
implementing agencies need not require that a very large percentage of
the range of estimated radiation exposures or radionuclide
concentrations fall below limits established in Sec. Sec. 191.15 and
191.16, respectively. The Agency assumes that compliance can be
determined based upon ``best estimate'' predictions (e.g., the mean or
the median of the appropriate distribution, whichever is higher).
Institutional Controls. To comply with Sec. 191.14(a), the
implementing agency will assume that none of the active institutional
controls prevent or reduce radionuclide releases for more than 100 years
after disposal. However, the Federal Government is committed to
retaining ownership of all disposal sites for spent nuclear fuel and
high-level and transuranic radioactive wastes and will establish
appropriate markers and records, consistent with Sec. 191.14(c). The
Agency assumes that, as long as such passive institutional controls
endure and are understood, they: (1) Can be effective in deterring
systematic or persistent exploitation of these
[[Page 17]]
disposal sites; and (2) can reduce the likelihood of inadvertent,
intermittent human intrusion to a degree to be determined by the
implementing agency. However, the Agency believes that passive
institutional controls can never be assumed to eliminate the chance of
inadvertent and intermittent human intrusion into these disposal sites.
Consideration of Inadvertent Human Intrusion into Geologic
Repositories. The most speculative potential disruptions of a mined
geologic repository are those associated with inadvertent human
intrusion. Some types of intrusion would have virtually no effect on a
repository's containment of waste. On the other hand, it is possible to
conceive of intrusions (involving widespread societal loss of knowledge
regarding radioactive wastes) that could result in major disruptions
that no reasonable repository selection or design precautions could
alleviate. The Agency believes that the most productive consideration of
inadvertent intrusion concerns those realistic possibilities that may be
usefully mitigated by repository design, site selection, or use of
passive controls (although passive institutional controls should not be
assumed to completely rule out the possibility of intrusion). Therefore,
inadvertent and intermittent intrusion by exploratory drilling for
resources (other than any provided by the disposal system itself) can be
the most severe intrusion scenario assumed by the implementing agencies.
Furthermore, the implementing agencies can assume that passive
institutional controls or the intruders' own exploratory procedures are
adequate for the intruders to soon detect, or be warned of, the
incompatibility of the area with their activities.
Frequency and Severity of Inadvertent Human Intrusion into Geologic
Repositories. The implementing agencies should consider the effects of
each particular disposal system's site, design, and passive
institutional controls in judging the likelihood and consequences of
such inadvertent exploratory drilling. However, the Agency assumes that
the likelihood of such inadvertent and intermittent drilling need not be
taken to be greater than 30 boreholes per square kilometer of repository
area per 10,000 years for geologic repositories in proximity to
sedimentary rock formations, or more than 3 boreholes per square
kilometer per 10,000 years for repositories in other geologic
formations. Furthermore, the Agency assumes that the consequences of
such inadvertent drilling need not be assumed to be more severe than:
(1) Direct release to the land surface of all the ground water in the
repository horizon that would promptly flow through the newly created
borehole to the surface due to natural lithostatic pressure--or (if
pumping would be required to raise water to the surface) release of 200
cubic meters of ground water pumped to the surface if that much water is
readily available to be pumped; and (2) creation of a ground water flow
path with a permeability typical of a borehole filled by the soil or
gravel that would normally settle into an open hole over time--not the
permeability of a carefully sealed borehole.
[50 FR 38084, Sept. 19, 1985. Redesignated and amended at 58 FR 66415,
Dec. 20, 1993]