Gilson and Voss - Voss Associates
Gilson and Voss - Voss Associates
Gilson and Voss - Voss Associates
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RULES OF THUMB FOR NEUTRONS<br />
1. The number of neutrons per square centimeter per second<br />
at distance R from a small source emitting Q neutrons per<br />
second without shielding is given by;<br />
2 2 2<br />
n / cm -sec = Q / 4R = 0.08Q / R<br />
2. For á, ç sources use the following equation to approximate<br />
the number of neutrons per second per Ci (Q).<br />
Q = 5.6E3 x (alpha particle energy in MeV) 3.65<br />
This holds true for Be; multiply by 0.16 for B targets, by 0.05<br />
for F, by 0.015 for Li, <strong>and</strong> 0.003 for O targets.<br />
3. For neutron energies from 1 to 10 MeV the neutron<br />
exposure rate is approximately equal to 1 mrem/hr at 1<br />
meter for each 1E6 neutrons per second emission rate.<br />
Multiply the neutron mrem/hr at 1 meter by 11.1 to calculate<br />
the neutron exposure rate for the same source at a distance<br />
of 30 cm.<br />
4. For spontaneous fission the gamma exposure rate for an<br />
unshielded source is approximately twice the neutron<br />
exposure rate.<br />
5. The range of neutrons in air for energies from 0 to 10 MeV<br />
is from a few centimeters to 100 meters.<br />
6. The range of neutrons in water (or tissue) for energies from<br />
0 to 10 MeV is from a few millimeters to 1 meter.<br />
7. Neutron flux to dose rate conversion:<br />
Fast:<br />
2<br />
1 mrem (0.01 mSv) / hr per 6 n / cm -sec<br />
Slow:<br />
2<br />
1 mrem (0.01 mSv) / hr per 272 n / cm -sec<br />
RULES OF THUMB FOR NEUTRONS<br />
1. The number of neutrons per square centimeter per second<br />
at distance R from a small source emitting Q neutrons per<br />
second without shielding is given by;<br />
2 2 2<br />
n / cm -sec = Q / 4R = 0.08Q / R<br />
2. For á, ç sources use the following equation to approximate<br />
the number of neutrons per second per Ci (Q).<br />
Q = 5.6E3 x (alpha particle energy in MeV) 3.65<br />
This holds true for Be; multiply by 0.16 for B targets, by 0.05<br />
for F, by 0.015 for Li, <strong>and</strong> 0.003 for O targets.<br />
3. For neutron energies from 1 to 10 MeV the neutron<br />
exposure rate is approximately equal to 1 mrem/hr at 1<br />
meter for each 1E6 neutrons per second emission rate.<br />
Multiply the neutron mrem/hr at 1 meter by 11.1 to calculate<br />
the neutron exposure rate for the same source at a distance<br />
of 30 cm.<br />
4. For spontaneous fission the gamma exposure rate for an<br />
unshielded source is approximately twice the neutron<br />
exposure rate.<br />
5. The range of neutrons in air for energies from 0 to 10 MeV<br />
is from a few centimeters to 100 meters.<br />
6. The range of neutrons in water (or tissue) for energies from<br />
0 to 10 MeV is from a few millimeters to 1 meter.<br />
7. Neutron flux to dose rate conversion:<br />
Fast:<br />
2<br />
1 mrem (0.01 mSv) / hr per 6 n / cm -sec<br />
Slow:<br />
2<br />
1 mrem (0.01 mSv) / hr per 272 n / cm -sec<br />
RULES OF THUMB FOR NEUTRONS<br />
1. The number of neutrons per square centimeter per second<br />
at distance R from a small source emitting Q neutrons per<br />
second without shielding is given by;<br />
2 2 2<br />
n / cm -sec = Q / 4R = 0.08Q / R<br />
2. For á, ç sources use the following equation to approximate<br />
the number of neutrons per second per Ci (Q).<br />
Q = 5.6E3 x (alpha particle energy in MeV) 3.65<br />
This holds true for Be; multiply by 0.16 for B targets, by 0.05<br />
for F, by 0.015 for Li, <strong>and</strong> 0.003 for O targets.<br />
3. For neutron energies from 1 to 10 MeV the neutron<br />
exposure rate is approximately equal to 1 mrem/hr at 1<br />
meter for each 1E6 neutrons per second emission rate.<br />
Multiply the neutron mrem/hr at 1 meter by 11.1 to calculate<br />
the neutron exposure rate for the same source at a distance<br />
of 30 cm.<br />
4. For spontaneous fission the gamma exposure rate for an<br />
unshielded source is approximately twice the neutron<br />
exposure rate.<br />
5. The range of neutrons in air for energies from 0 to 10 MeV<br />
is from a few centimeters to 100 meters.<br />
6. The range of neutrons in water (or tissue) for energies from<br />
0 to 10 MeV is from a few millimeters to 1 meter.<br />
7. Neutron flux to dose rate conversion:<br />
Fast:<br />
2<br />
1 mrem (0.01 mSv) / hr per 6 n / cm -sec<br />
Slow:<br />
2<br />
1 mrem (0.01 mSv) / hr per 272 n / cm -sec<br />
RULES OF THUMB FOR NEUTRONS<br />
1. The number of neutrons per square centimeter per second<br />
at distance R from a small source emitting Q neutrons per<br />
second without shielding is given by;<br />
2 2 2<br />
n / cm -sec = Q / 4R = 0.08Q / R<br />
2. For á, ç sources use the following equation to approximate<br />
the number of neutrons per second per Ci (Q).<br />
Q = 5.6E3 x (alpha particle energy in MeV) 3.65<br />
This holds true for Be; multiply by 0.16 for B targets, by 0.05<br />
for F, by 0.015 for Li, <strong>and</strong> 0.003 for O targets.<br />
3. For neutron energies from 1 to 10 MeV the neutron<br />
exposure rate is approximately equal to 1 mrem/hr at 1<br />
meter for each 1E6 neutrons per second emission rate.<br />
Multiply the neutron mrem/hr at 1 meter by 11.1 to calculate<br />
the neutron exposure rate for the same source at a distance<br />
of 30 cm.<br />
4. For spontaneous fission the gamma exposure rate for an<br />
unshielded source is approximately twice the neutron<br />
exposure rate.<br />
5. The range of neutrons in air for energies from 0 to 10 MeV<br />
is from a few centimeters to 100 meters.<br />
6. The range of neutrons in water (or tissue) for energies from<br />
0 to 10 MeV is from a few millimeters to 1 meter.<br />
7. Neutron flux to dose rate conversion:<br />
Fast:<br />
2<br />
1 mrem (0.01 mSv) / hr per 6 n / cm -sec<br />
Slow:<br />
2<br />
1 mrem (0.01 mSv) / hr per 272 n / cm -sec
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