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APPENDIX C TO PART 835—DERIVED AIR
CONCENTRATION (DAC) FOR WORK-
The air immersion DAC values shown in this appendix are based on a stochastic limit of 5 rems (0.05 Sv) per year or a nonstochastic (organ) dose limit of 50 rems (0.5 Sv) per year. Four columns of information are presented: (1) Radionuclide; (2) halflife in units of seconds (8), minutes (min),
hours (h), days (d), or years (yr); (3) air immersion DAC in units of uCi/ml; and (4) air immersion DAC in units of Bq/m3. The data are listed by radionuclide in order of increasing atomic mass. The air immersion DACs were calculated for a continuous, nonshielded exposure via immersion in a semi-infinite atmospheric cloud.
The DAC value for air immersion listed for a given radionuclide is determined either by a yearly limit on effective dose equivalent, which provides a limit on stochastic radiation effects, or by a limit on yearly dose equivalent to any organ, which provides a
limit on nonstochastic radiation effects. For most of the radionuclides listed, the DAC value is determined by the yearly limit on effective dose equivalent. Thus, the few cases where the DAC value is determined by the yearly limit on shallow dose equivalent to the skin are indicated in the table by an ap propriate footnote. Again, the DACs listed in this appendix account only for immersion in a semi-infinite cloud and do not account for inhalation or ingestion exposures.
Three classes of radionuclides are included in the air immersion DACs as described below.
(1) Class 1. The first class of radionuclides includes selected noble gases and short-lived activation products that occur in gaseous form. For these radionuclides, inhalation doses are negligible compared to the external dose from immersion in an atmospheric
value). These radionuclides generally have half-lives of a few hours or less, or are elimi. nated from the body following inhalation sufficiently rapidly to limit the inhalation dose.
(3) Class 3. The third class of radionuclides includes selected isotopes with relatively short half-lives. These radionuclides typically have half-lives that are less than 10 minutes, they do not occur as a decay product of a longer lived radionuclide, or they lack sufficient decay data to permit internal dose calculations. These radionuclides are also typified by a radioactive emission of highly intense, high-energy photons and rapid removal from the body following inhalation.
The DAC values are given for individual radionuclides. For known mixtures of radio nuclides, the sum of the ratio of the observed concentration of a particular radionuclide and its corresponding DAC for all radionuclides in the mixture must not exceed 1.0. For unknown radionuclides, the most restrictive DAC (lowest value) for those isotopes not known to be absent shall be used.
Air Immersion DAC (Ciml) (Bom)
20.48 min ... 9.97 min ..... 7.13 $ ............*** 122.24 S ............................................................................................................. 109.74 min ..... 15.00 h ....... 9.458 min ............. 2.240 min 37.21 min ...................... 35.02 d.......
1.827 h ......
22.6 h ....... | 8.719 min ....
3.927 h.. 18.72 8 ... 3.08 h .............................. 5.752 min ... 3.75 min ....... 42.09 min 21.4 min ..... 2.5785 h ..... 1.47 min ... 10.47 min ..... 36.08 h .. 2.520 h .. 3.408 h ...... 9.74 min .... 9.40 h 68.0 min ....... 14.1 h ..... 7.15 h. 57.04 h ........ 17.4 min ... 35.30 h ........ 31.80 min ........... 172 s 35.04 h 2.1E+05 y ............
Air Immersion DAC Radionuclide
(u Cimi) (Bom) L-1421 95.4 min .......
4.E+04 PT-144m2 7.2 min .......
3.E+07 Nd_1491 1.73 h
4.E+05 Gd-1622 9.7 min ....
4.E+05 Td-1622 7.76 min .................
1.E+05 Dy-1571 8.06 h
4.E+05 Re-182m 1 12.7 h
1.E+05 Os-190m2 9.9 min ......
1.E+05 Ir-190m 3.2 h
3.E+066 Au-196m2 30.6 S ....
7.E+05 TI-2001 26.1 h .....
1.E+05 TI-2072 4.77 min
1.E+063 TI-2082 3.053 min .....
4.E+04 T-2092 2.20 min
2.E-06 7.E+04 TH-2102 1.30 min ....
4.E+04 Pb-204m2 66.9 min ....
7.E+04 B12112 2.13 min ......
4.E+08 Po-2112 0.516 s...
2.E+07 Rn-220 55.61 s ....
3.E+026 Rn-222 3.824 d.
1.E+036 Th-2332 22.3 min .......
4.E+06 Pa-2341 6.70 h.
7.E+04 Pa-234m2 1.17 min
4.E-053 1.E+06) U-2391 23.40 min
3.E+066 Np-240 65 min
1.E+05 Np-240m 2 7.4 min .....
4.E+05 Am-2461 25.0 min ........
1.E+05 Committed effective dose equivalent from inhalation is calculated in ICRP Publication 30, but the DAC value for external exposure to a contaminated atmospheric cloud is more restrictive than the DAC value for inhalation.
2 Committed effective dose equivalent from inhalation is not calculated in ICRP Publication 30. but DAC value for extemal exposure to contaminated cloud should be more restrictive than DAC value for inhalation due to relatively short half-life of radio nuclide.
DAC value is determined by limit on annual shallow dose equivalent to skin, rather than yearly limit on effective dose equiva lent.
*DAC value applies to radionuclide in vapor form only; DAC value for inhalation is more restrictive for radionuclide in inorganic form. 6 DAC value applies to radionuclide in inorganic or vapor form. DAC value for exposure to contaminated atmospheric dloud is the same as DAC value for inhalation.
Unat, U-235, U-238, and associated decay products
5.000 Transuranics, Ra-226, Ra-228, TH-230, TH-228, Pa-231, AC-227, 1-125, 1-129 ......
500 Th-na, Th-20, 800, Ram, Ra-24, U-22, E125, F131, E183 .........
1.000 Beta gamma emitters (nuclides with decay modes other than alpha emission or spontaneous fission) except Sr-90 and others noted above. .
5,000 Tritium Organic Compounds; surfaces contaminated by HT, HTO, and metal tritide aerosols ... (Reserved) (Reserved)
The values in this appendix apply to radioactive contamination deposited on, but not incorporated into the interior of, the con taminated item. Where surface contamination by both alpha- and beta-gamma emitting nuclides exists, the limits established for alpha and beta-gamma emitting nuclides should apply independently.
2 As used in this table, dpm (disintegrations per minute) means the rate of emission by radioactive material as determined by correcting the counts per minute observed by an appropriate detector for background, efficiency, and geometric factors assoc ated with the instrumentation.
The levels may be averaged over one square meter provided the maximum surface activity in any area of 100 cm? is less than three times the value specified. For purposes of averaging, any square meter of surface shall be considered to be above the activity ouide Git: (1) From measurements of a representative number n of sections it is determined that th , S, 2 G, where S, is the dpm/100 cm? determined from measurement of section i; or (2) it is determined that the sum of the activity of all isolated spots or particles in any 100 cm2 area exceeds 3G.
*The amount of removable radioactive material per 100 cm? of surface area should be determined by swiping the area with dry filter or soft absorbent paper, applying moderate pressure, and then assessing the amount of radioactive material on the swipe with an appropriate instrument of known efficiency. (Note-The use of dry material may not be appropriate for trítium.) When removable contamination on objects of surface area less than 100 cm ? is determined, the activity per unit area should be based on the actual area and the entire surface should be wiped. Except for transuranics and Ra-228, Ac-227, Th-228, Th-230, Pa-231 and alpha emitters, it is not necessary to use swiping techniques to measure removable contamination levels is direct scan surveys indicate that the total residual surface contamination levels are within the limits for removable contarnination. This category of radionuclides includes mixed fission products, including the Sr-90 which is present in them. It does not apply
rom the other fission products or mixtures where the Sr-90 has been enriched.
APPENDIX E TO PART 835—[RESERVED) which would be expected to cause sub
stantial injury or damage unless it exPART 840-EXTRAORDINARY ceeds by some significant multiple the NUCLEAR OCCURRENCES appropriate regulatory limit. Accord
ingly, in arriving at the values in the Sec.
criteria to be deemed "substantial" it 840.1 Scope and purpose.
is more appropriate to adopt values 840.2 Procedures.
separate from DOE health and safety 840.3 Determination of extraordinary nu orders, and, of course the selection of clear occurrence.
these values will not in any way affect 840.4 Criterion Substantial discharge of
such orders. A substantial discharge, radioactive material or substantial radi. ation levels offsite.
for purposes of the criteria, represents 840.5 Criterion 01-Substantial damages to
a perturbation of the environment persons offsite or property offsite.
which is clearly above that which could
be anticipated from the conduct of norAUTHORITY: Sec. 161 of the Atomic Energy Act of 1954, Pub. L. 83–703, 68 Stat. 919 (42
mal activities. The criteria are inU.S.C. 2201); sec. 170 of the Atomic Energy
tended solely for the purposes of adAct of 1954, Pub. L. 85–256, 71 Stat. 576, as ministration of DOE statutory responamended by Pub. L. 89 645, 80 Stat. 891 (42 sibilities under Pub. L. 89-645, and are U.S.C. 2210); Department of Energy Organiza not intended to indicate a level of distion Act, Pub. L. 96-91, 91 Stat. 565 613 (42 charge or dispersal at which damage is U.S.C. 7101-7352).
likely to occur, or even a level at SOURCE: 49 FR 21473, May 21, 1984, unless which some type of protective action is otherwise noted.
indicated. It should be clearly under
stood that the criteria in no way estab8840.1 Scope and purpose.
lish or indicate that there is a specific (a) Scope. This subpart applies to threshold of exposure at which biologithose DOE contractor activities to cal damage from radiation will take which the nuclear hazards indemnity place. It cannot be emphasized too freprovisions in 41 CFR 950.704-6 apply, quently that the levels set to be used and to other persons indemnified with as criteria for the first part of the derespect to such activities.
termination, that is, the criteria for (b) Purpose. One purpose of this sub amounts offsite or radiation levels offpart is to set forth the criteria which site which are substantial, are not the DOE proposes to follow in order to meant to indicate that, because such determine whether there has been an amounts or levels are determined to be "extraordinary nuclear occurrence." substantial for purposes of administraThe other purpose is to establish the tion, they are “substantial” in terms conditions of the waivers of defenses of their propensity for causing injury proposed for incorporation in indem- or damage. nity agreements.
(2) It is the purpose of the second (1) The system is to come into effect part of the determination that DOE deonly where the discharge or dispersal cide whether there have in fact been or constitutes a substantial amount of will probably be substantial damages source, special nuclear or byproduct to persons offsite or property offsite. material, or has caused substantial ra- The criteria for substantial damages diation levels offsite. The various lim- were formulated, and the numerical its in present DOE regulations are not values selected, on a wholly different appropriate for direct application in basis from that on which the criteria the determination of an “extraordinary used for the first part of the determinanuclear occurrence," for they were ar- tion with respect to substantial disrived at with other purposes in mind, charge were derived. The only interand those limits have been set at a relation between the values selected level which is conservatively arrived at for the discharge criteria and the damby incorporating a significant safety age criteria is that the discharge valfactor. Thus, & discharge or dispersalues are set so low that it is extremely which exceeds the limits in DOE regu- unlikely the damage criteria could be lations, or in DOE orders, although satisfied unless the discharge values possible cause for concern, is not one have been exceeded.