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Naturally occurring
Oxidation-enhanced emission of ruthenium from nuclear fuel
Journal of Environmental Radioactivity, 26(1), 63-70.Backman, U., Lipponen, M., Auvinen, A., Jokiniemi, J., & Zilliacus, R. (2004)
Ruthenium behaviour in severe nuclear accident conditions
Final report (No. NKS–100). Nordisk Kernesikkerhedsforskning.Beuzet, E., Lamy, J. S., Perron, H., Simoni, E., & Ducros, G. (2012)
Ruthenium release modelling in air and steam atmospheres under severe accident conditions using the MAAP4 code
Nuclear Engineering and Design, 246, 157-162. The two most important isotopes of ruthenium in case of nuclear accident are these with the longest half-life: 103Ru (39.26 days) and 106Ru (373.59 days).
400 ns, , , 3/2−# , , , -id=Ruthenium-86 , 86Ru , style="text-align:right" , 44 , style="text-align:right" , 42 , 85.95731(43)# , 50# ms
400 ns, , , 0+ , , , -id=Ruthenium-87 , 87Ru , style="text-align:right" , 44 , style="text-align:right" , 43 , 86.95091(43)# , 50# ms
1.5 μs, , , 1/2−# , , , -id=Ruthenium-88 , rowspan=2, 88Ru , rowspan=2 style="text-align:right" , 44 , rowspan=2 style="text-align:right" , 44 , rowspan=2, 87.94166(32)# , rowspan=2, 1.5(3) s , β+ (>96.4%) , 88Tc , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β+, p (<3.6%) , 87Mo , -id=Ruthenium-89 , rowspan=2, 89Ru , rowspan=2 style="text-align:right" , 44 , rowspan=2 style="text-align:right" , 45 , rowspan=2, 88.937338(26) , rowspan=2, 1.32(3) s , β+ (96.7%) , 89Tc , rowspan=2, (9/2+) , rowspan=2, , rowspan=2, , - , β+, p (3.1%) , 88Mo , -id=Ruthenium-90 , 90Ru , style="text-align:right" , 44 , style="text-align:right" , 46 , 89.9303444(40) , 11.7(9) s , β+ , 90Tc , 0+ , , , -id=Ruthenium-91 , 91Ru , style="text-align:right" , 44 , style="text-align:right" , 47 , 90.9267415(24) , 8.0(4) s , β+ , 91Tc , (9/2+) , , , -id=Ruthenium-91m , rowspan=2 style="text-indent:1em" , 91mRuOrder of ground state and isomer is uncertain. , rowspan=2 colspan="3" style="text-indent:2em" , −340(500) keV , rowspan=2, 7.6(8) s , β+ (>99.9%) , 91Tc , rowspan=2, (1/2−) , rowspan=2, , rowspan=2, , - , β+, p (?%) , 90Mo , -id=Ruthenium-92 , 92Ru , style="text-align:right" , 44 , style="text-align:right" , 48 , 91.9202344(29) , 3.65(5) min , β+ , 92Tc , 0+ , , , -id=Ruthenium-92m , style="text-indent:1em" , 92mRu , colspan="3" style="text-indent:2em" , 2833.9(18) keV , 100(8) ns , IT , 92Ru , (8+) , , , -id=Ruthenium-93 , 93Ru , style="text-align:right" , 44 , style="text-align:right" , 49 , 92.9171044(22) , 59.7(6) s , β+ , 93Tc , (9/2)+ , , , -id=Ruthenium-93m1 , rowspan=3 style="text-indent:1em" , 93m1Ru , rowspan=3 colspan="3" style="text-indent:2em" , 734.40(10) keV , rowspan=3, 10.8(3) s , β+ (78.0%) , 93Tc , rowspan=3, (1/2)− , rowspan=3, , rowspan=3, , - , IT (22.0%) , 93Ru , - , β+, p (0.027%) , 92Mo , -id=Ruthenium-93m2 , style="text-indent:1em" , 93m2Ru , colspan="3" style="text-indent:2em" , 2082.5(9) keV , 2.30(7) μs , IT , 93Ru , (21/2)+ , , , -id=Ruthenium-94 , 94Ru , style="text-align:right" , 44 , style="text-align:right" , 50 , 93.9113429(34) , 51.8(6) min , β+ , 94Tc , 0+ , , , -id=Ruthenium-94m , style="text-indent:1em" , 94mRu , colspan="3" style="text-indent:2em" , 2644.1(4) keV , 67.5(28) μs , IT , 94Ru , 8+ , , , -id=Ruthenium-95 , 95Ru , style="text-align:right" , 44 , style="text-align:right" , 51 , 94.910404(10) , 1.607(4) h , β+ , 95Tc , 5/2+ , , , -id=Ruthenium-96 , 96Ru , style="text-align:right" , 44 , style="text-align:right" , 52 , 95.90758891(18) , colspan=3 align=center,
550 ns, , , 3/2+# , , * In September 2017 an estimated amount of 100 to 300 TBq (0.3 to 1 g) of 106Ru was released in Russia, probably in the Ural region. It was, after ruling out release from a reentering satellite, concluded that the source is to be found either in nuclear fuel cycle facilities or radioactive source production. In France levels up to 0.036mBq/m3 of air were measured. It is estimated that over distances of the order of a few tens of kilometres around the location of the release levels may exceed the limits for non-dairy foodstuffs.
Detection of ruthenium 106 in France and in Europe, IRSN France (9 Nov 2017)
ruthenium
Ruthenium is a chemical element; it has symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is unreactive to most chem ...
(44Ru) is composed of seven stable isotope
Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...
s (of which two may in the future be found radioactive). Additionally, 27 radioactive isotopes have been discovered. Of these radioisotope
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...
s, the most stable are 106Ru, with a half-life Half-life is a mathematical and scientific description of exponential or gradual decay.
Half-life, half life or halflife may also refer to:
Film
* Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang
* ''Half Life: ...
of 373.59 days; 103Ru, with a half-life of 39.26 days and 97Ru, with a half-life of 2.9 days.
Twenty-four other radioisotopes have been characterized with atomic weight
Relative atomic mass (symbol: ''A''; sometimes abbreviated RAM or r.a.m.), also known by the deprecated synonym atomic weight, is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a giv ...
s ranging from 86.95 u (87Ru) to 119.95 u (120Ru). Most of these have half-lives that are less than five minutes, except 94Ru (half-life: 51.8 minutes), 95Ru (half-life: 1.643 hours), and 105Ru (half-life: 4.44 hours).
The primary decay mode
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...
before the most abundant isotope, 102Ru, is electron capture
Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. Th ...
and the primary mode after is beta emission
In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which an atomic nucleus emits a beta particle (fast energetic electron or positron), transforming into an isobar of that nuclide. For example, beta decay of a neutron t ...
. The primary decay product
In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( d ...
before 102Ru is technetium
Technetium is a chemical element; it has Symbol (chemistry), symbol Tc and atomic number 43. It is the lightest element whose isotopes are all radioactive. Technetium and promethium are the only radioactive elements whose neighbours in the sense ...
and the primary product after is rhodium
Rhodium is a chemical element; it has symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring isot ...
.
Because of the very high volatility of ruthenium tetroxide
Ruthenium tetroxide is the inorganic compound with the formula RuO4. It is a yellow volatile solid that melts near room temperature. It has the odor of ozone. Samples are typically black due to impurities. The analogous OsO4 is more widely used a ...
() ruthenium radioactive isotopes with their relative short half-life are considered as the second most hazardous gaseous isotopes after iodine-131
Iodine-131 (131I, I-131) is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. It has a radioactive decay half-life of about eight days. It is associated with nu ...
in case of release by a nuclear accident.Ronneau, C., Cara, J., & Rimski-Korsakov, A. (1995)Oxidation-enhanced emission of ruthenium from nuclear fuel
Journal of Environmental Radioactivity, 26(1), 63-70.Backman, U., Lipponen, M., Auvinen, A., Jokiniemi, J., & Zilliacus, R. (2004)
Ruthenium behaviour in severe nuclear accident conditions
Final report (No. NKS–100). Nordisk Kernesikkerhedsforskning.Beuzet, E., Lamy, J. S., Perron, H., Simoni, E., & Ducros, G. (2012)
Ruthenium release modelling in air and steam atmospheres under severe accident conditions using the MAAP4 code
Nuclear Engineering and Design, 246, 157-162. The two most important isotopes of ruthenium in case of nuclear accident are these with the longest half-life: 103Ru (39.26 days) and 106Ru (373.59 days).
List of isotopes
, -id=Ruthenium-85 , 85Ru , style="text-align:right" , 44 , style="text-align:right" , 41 , 84.96712(54)# , 1# ms400 ns, , , 3/2−# , , , -id=Ruthenium-86 , 86Ru , style="text-align:right" , 44 , style="text-align:right" , 42 , 85.95731(43)# , 50# ms
400 ns, , , 0+ , , , -id=Ruthenium-87 , 87Ru , style="text-align:right" , 44 , style="text-align:right" , 43 , 86.95091(43)# , 50# ms
1.5 μs, , , 1/2−# , , , -id=Ruthenium-88 , rowspan=2, 88Ru , rowspan=2 style="text-align:right" , 44 , rowspan=2 style="text-align:right" , 44 , rowspan=2, 87.94166(32)# , rowspan=2, 1.5(3) s , β+ (>96.4%) , 88Tc , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β+, p (<3.6%) , 87Mo , -id=Ruthenium-89 , rowspan=2, 89Ru , rowspan=2 style="text-align:right" , 44 , rowspan=2 style="text-align:right" , 45 , rowspan=2, 88.937338(26) , rowspan=2, 1.32(3) s , β+ (96.7%) , 89Tc , rowspan=2, (9/2+) , rowspan=2, , rowspan=2, , - , β+, p (3.1%) , 88Mo , -id=Ruthenium-90 , 90Ru , style="text-align:right" , 44 , style="text-align:right" , 46 , 89.9303444(40) , 11.7(9) s , β+ , 90Tc , 0+ , , , -id=Ruthenium-91 , 91Ru , style="text-align:right" , 44 , style="text-align:right" , 47 , 90.9267415(24) , 8.0(4) s , β+ , 91Tc , (9/2+) , , , -id=Ruthenium-91m , rowspan=2 style="text-indent:1em" , 91mRuOrder of ground state and isomer is uncertain. , rowspan=2 colspan="3" style="text-indent:2em" , −340(500) keV , rowspan=2, 7.6(8) s , β+ (>99.9%) , 91Tc , rowspan=2, (1/2−) , rowspan=2, , rowspan=2, , - , β+, p (?%) , 90Mo , -id=Ruthenium-92 , 92Ru , style="text-align:right" , 44 , style="text-align:right" , 48 , 91.9202344(29) , 3.65(5) min , β+ , 92Tc , 0+ , , , -id=Ruthenium-92m , style="text-indent:1em" , 92mRu , colspan="3" style="text-indent:2em" , 2833.9(18) keV , 100(8) ns , IT , 92Ru , (8+) , , , -id=Ruthenium-93 , 93Ru , style="text-align:right" , 44 , style="text-align:right" , 49 , 92.9171044(22) , 59.7(6) s , β+ , 93Tc , (9/2)+ , , , -id=Ruthenium-93m1 , rowspan=3 style="text-indent:1em" , 93m1Ru , rowspan=3 colspan="3" style="text-indent:2em" , 734.40(10) keV , rowspan=3, 10.8(3) s , β+ (78.0%) , 93Tc , rowspan=3, (1/2)− , rowspan=3, , rowspan=3, , - , IT (22.0%) , 93Ru , - , β+, p (0.027%) , 92Mo , -id=Ruthenium-93m2 , style="text-indent:1em" , 93m2Ru , colspan="3" style="text-indent:2em" , 2082.5(9) keV , 2.30(7) μs , IT , 93Ru , (21/2)+ , , , -id=Ruthenium-94 , 94Ru , style="text-align:right" , 44 , style="text-align:right" , 50 , 93.9113429(34) , 51.8(6) min , β+ , 94Tc , 0+ , , , -id=Ruthenium-94m , style="text-indent:1em" , 94mRu , colspan="3" style="text-indent:2em" , 2644.1(4) keV , 67.5(28) μs , IT , 94Ru , 8+ , , , -id=Ruthenium-95 , 95Ru , style="text-align:right" , 44 , style="text-align:right" , 51 , 94.910404(10) , 1.607(4) h , β+ , 95Tc , 5/2+ , , , -id=Ruthenium-96 , 96Ru , style="text-align:right" , 44 , style="text-align:right" , 52 , 95.90758891(18) , colspan=3 align=center,
Observationally Stable
Stable nuclides are isotopes of a chemical element whose nucleons are in a configuration that does not permit them the surplus energy required to produce a radioactive emission. The nuclei of such isotopes are not radioactive and unlike radionuc ...
Believed to undergo β+β+ decay to 96Mo with a half-life over 8×1019 years
, 0+
, 0.0554(14)
,
, -id=Ruthenium-97
, 97Ru
, style="text-align:right" , 44
, style="text-align:right" , 53
, 96.9075458(30)
, 2.8370(14) d
, β+
, 97Tc
, 5/2+
,
,
, -id=Ruthenium-98
, 98Ru
, style="text-align:right" , 44
, style="text-align:right" , 54
, 97.9052867(69)
, colspan=3 align=center, Stable
, 0+
, 0.0187(3)
,
, -id=Ruthenium-99
, 99Ru
, style="text-align:right" , 44
, style="text-align:right" , 55
, 98.90593028(37)
, colspan=3 align=center, Stable
, 5/2+
, 0.1276(14)
,
, -id=Ruthenium-100
, 100Ru
, style="text-align:right" , 44
, style="text-align:right" , 56
, 99.90421046(37)
, colspan=3 align=center, Stable
, 0+
, 0.1260(7)
,
, -id=Ruthenium-101
, 101RuFission product
Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the releas ...
, style="text-align:right" , 44
, style="text-align:right" , 57
, 100.90557309(44)
, colspan=3 align=center, Stable
, 5/2+
, 0.1706(2)
,
, -id=Ruthenium-101m
, style="text-indent:1em" , 101mRu
, colspan="3" style="text-indent:2em" , 527.56(10) keV
, 17.5(4) μs
, IT
, 101Ru
, 11/2−
,
,
, -id=Ruthenium-102
, 102Ru
, style="text-align:right" , 44
, style="text-align:right" , 58
, 101.90434031(45)
, colspan=3 align=center, Stable
, 0+
, 0.3155(14)
,
, -id=Ruthenium-103
, 103Ru
, style="text-align:right" , 44
, style="text-align:right" , 59
, 102.90631485(47)
, 39.245(8) d
, β−
, 103Rh
, 3/2+
,
,
, -id=Ruthenium-103m
, style="text-indent:1em" , 103mRu
, colspan="3" style="text-indent:2em" , 238.2(7) keV
, 1.69(7) ms
, IT
, 103Ru
, 11/2−
,
,
, -id=Ruthenium-104
, 104Ru
, style="text-align:right" , 44
, style="text-align:right" , 60
, 103.9054253(27)
, colspan=3 align=center, Observationally StableBelieved to undergo β−β− decay to 104Pd
, 0+
, 0.1862(27)
,
, -id=Ruthenium-105
, 105Ru
, style="text-align:right" , 44
, style="text-align:right" , 61
, 104.9077455(27)
, 4.439(11) h
, β−
, 105Rh
, 3/2+
,
,
, -id=Ruthenium-105m
, style="text-indent:1em" , 105mRu
, colspan="3" style="text-indent:2em" , 20.606(14) keV
, 340(15) ns
, IT
, 105Ru
, 5/2+
,
,
, -id=Ruthenium-106
, 106Ru
, style="text-align:right" , 44
, style="text-align:right" , 62
, 105.9073282(58)
, 371.8(18) d
, β−
, 106Rh
, 0+
,
,
, -id=Ruthenium-107
, 107Ru
, style="text-align:right" , 44
, style="text-align:right" , 63
, 106.9099698(93)
, 3.75(5) min
, β−
, 107Rh
, (5/2)+
,
,
, -id=Ruthenium-108
, 108Ru
, style="text-align:right" , 44
, style="text-align:right" , 64
, 107.9101858(93)
, 4.55(5) min
, β−
, 108Rh
, 0+
,
,
, -id=Ruthenium-109
, 109Ru
, style="text-align:right" , 44
, style="text-align:right" , 65
, 108.9133237(96)
, 34.4(2) s
, β−
, 109Rh
, (5/2+)
,
,
, -id=Ruthenium-109m
, style="text-indent:1em" , 109mRu
, colspan="3" style="text-indent:2em" , 96.14(15) keV
, 680(30) ns
, IT
, 109Ru
, (5/2−)
,
,
, -id=Ruthenium-110
, 110Ru
, style="text-align:right" , 44
, style="text-align:right" , 66
, 109.9140385(96)
, 12.04(17) s
, β−
, 110Rh
, 0+
,
,
, -id=Ruthenium-111
, 111Ru
, style="text-align:right" , 44
, style="text-align:right" , 67
, 110.917568(10)
, 2.12(7) s
, β−
, 111Rh
, 5/2+
,
,
, -id=Ruthenium-112
, 112Ru
, style="text-align:right" , 44
, style="text-align:right" , 68
, 111.918807(10)
, 1.75(7) s
, β−
, 112Rh
, 0+
,
,
, -id=Ruthenium-113
, 113Ru
, style="text-align:right" , 44
, style="text-align:right" , 69
, 112.922847(41)
, 0.80(5) s
, β−
, 113Rh
, (1/2+)
,
,
, -id=Ruthenium-113m
, rowspan=2 style="text-indent:1em" , 113mRu
, rowspan=2 colspan="3" style="text-indent:2em" , 131(33) keV
, rowspan=2, 510(30) ms
, β− (?%)
, 113Rh
, rowspan=2, (7/2−)
, rowspan=2,
, rowspan=2,
, -
, IT (?%)
, 113Ru
, -id=Ruthenium-114
, 114Ru
, style="text-align:right" , 44
, style="text-align:right" , 70
, 113.9246144(38)
, 0.54(3) s
, β−
, 114Rh
, 0+
,
,
, -id=Ruthenium-115
, 115Ru
, style="text-align:right" , 44
, style="text-align:right" , 71
, 114.929033(27)
, 318(19) ms
, β−
, 115Rh
, (1/2+)
,
,
, -id=Ruthenium-115m
, rowspan=2 style="text-indent:1em" , 115mRu
, rowspan=2 colspan="3" style="text-indent:2em" , 82(6) keV
, rowspan=2, 76(6) ms
, β− (?%)
, 115Rh
, rowspan=2, (7/2−)
, rowspan=2,
, rowspan=2,
, -
, IT (?%)
, 115Ru
, -id=Ruthenium-116
, 116Ru
, style="text-align:right" , 44
, style="text-align:right" , 72
, 115.9312192(40)
, 204(6) ms
, β−
, 116Rh
, 0+
,
,
, -id=Ruthenium-117
, 117Ru
, style="text-align:right" , 44
, style="text-align:right" , 73
, 116.93614(47)
, 151(3) ms
, β−
, 117Rh
, 3/2+#
,
,
, -id=Ruthenium-117m
, style="text-indent:1em" , 117mRu
, colspan="3" style="text-indent:2em" , 185.0(4) keV
, 2.49(6) μs
, IT
, 117Ru
, 7/2−#
,
,
, -id=Ruthenium-118
, 118Ru
, style="text-align:right" , 44
, style="text-align:right" , 74
, 117.93881(22)#
, 99(3) ms
, β−
, 118Rh
, 0+
,
,
, -id=Ruthenium-119
, 119Ru
, style="text-align:right" , 44
, style="text-align:right" , 75
, 118.94409(32)#
, 69.5(20) ms
, β−
, 119Rh
, 3/2+#
,
,
, -id=Ruthenium-119m
, style="text-indent:1em" , 119mRu
, colspan="3" style="text-indent:2em" , 227.1(7) keV
, 384(22) ns
, IT
, 119Ru
,
,
,
, -id=Ruthenium-120
, 120Ru
, style="text-align:right" , 44
, style="text-align:right" , 76
, 119.94662(43)#
, 45(2) ms
, β−
, 120Rh
, 0+
,
,
, -id=Ruthenium-121
, 121Ru
, style="text-align:right" , 44
, style="text-align:right" , 77
, 120.95210(43)#
, 29(2) ms
, β−
, 121Rh
, 3/2+#
,
,
, -id=Ruthenium-122
, 122Ru
, style="text-align:right" , 44
, style="text-align:right" , 78
, 121.95515(54)#
, 25(1) ms
, β−
, 122Rh
, 0+
,
,
, -id=Ruthenium-123
, 123Ru
, style="text-align:right" , 44
, style="text-align:right" , 79
, 122.96076(54)#
, 19(2) ms
, β−
, 123Rh
, 3/2+#
,
,
, -id=Ruthenium-124
, 124Ru
, style="text-align:right" , 44
, style="text-align:right" , 80
, 123.96394(64)#
, 15(3) ms
, β−
, 124Rh
, 0+
,
,
, -id=Ruthenium-125
, 125Ru
, style="text-align:right" , 44
, style="text-align:right" , 81
, 124.96954(32)#
, 12# ms550 ns, , , 3/2+# , , * In September 2017 an estimated amount of 100 to 300 TBq (0.3 to 1 g) of 106Ru was released in Russia, probably in the Ural region. It was, after ruling out release from a reentering satellite, concluded that the source is to be found either in nuclear fuel cycle facilities or radioactive source production. In France levels up to 0.036mBq/m3 of air were measured. It is estimated that over distances of the order of a few tens of kilometres around the location of the release levels may exceed the limits for non-dairy foodstuffs.
Detection of ruthenium 106 in France and in Europe, IRSN France (9 Nov 2017)
See also
Daughter products other than ruthenium *Isotopes of rhodium
Naturally occurring rhodium (45Rh) is composed of only one stable isotope, 103Rh. The most stable radioisotopes are 101Rh with a half-life of 3.3 years, 102Rh with a half-life of 207 days, and 99Rh with a half-life of 16.1 days. Thirty other radi ...
* Isotopes of technetium
Isotopes are distinct nuclear species (or '' nuclides'') of the same chemical element. They have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), b ...
* Isotopes of molybdenum
Molybdenum (42Mo) has 39 known isotopes, ranging in atomic mass from 81 to 119, as well as four metastable nuclear isomers. Seven isotopes occur naturally, with atomic masses of 92, 94, 95, 96, 97, 98, and 100. All unstable isotopes of molybdenum ...
References
* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Navbox element isotopes RutheniumRuthenium
Ruthenium is a chemical element; it has symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is unreactive to most chem ...