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LLE Safety Zone

Radiological Safety

Requirements come from the Nuclear Regulatory Commission (NRC), Environmental Protection Agency, and Department of Transportation
New York State has accepted regulatory authority from the NRC.
- NYS Department of Health (DOH) governs the use of radioactive material and radiation-producing devices in NYS
- Department of Environmental Conservation governs the release of radioactive material to the general public
University of Rochester is licensed by the NYS DOH
- UR’s Radiation Safety Unit (RSU) administers the University’s radiation safety program.
- UR’s Radiation Safety Committee establishes the procedures for the RSU and oversees their operations.
- LLE operates under a permit issued by the RSU

Types of radiation
Type	Mass	Charge	Penetrating ability	Shielding
Alpha	4	+2	Very low	Skin, paper
Beta	~0.0003	±1	Low	Clothing, plastic
Gamma	0	0	High	Lead, water
Neutron	1	0	High	Water, plastic

Activity: number of transformations per unit time
Curie: 3.7 x 10¹⁰ disintegrations per second
Dose: the energy imparted to matter by radiation
Rad: unit of dose equal to absorption of 100 ergs/gram of material
Dose equivalent: biological damage caused by absorbed dose
DE = dose x quality factor,
Where: QF = 1 for gamma and beta
= 20 for alpha
= 3 to 10 for neutrons
rem – roentgen equivalent man, a unit of dose equivalent
1 rem = 100 erg/gram of biological equivalent damage
Half-life: time required for activity of a substance to decrease by half

Neutron radiation from fusion
- Maximum credible yield shot of 3 x 10¹⁵ neutrons yields 516 rem at surface of the OMEGA target chamber (OMEGA EP maximum is ~10¹²neutrons)
Gamma radiation from neutron activation of structural components
- Principal sources are Na²⁴ (15 d) and Mn⁵⁴ (312 d)
- Maximum radiation after ten years not expected to exceed 5 mr/hr shortly after a target shot
Beta radiation from tritium
- Up to 15,000 Ci in Tritium Fill Station
High-energy x-ray radiation (up to 10 MeV) via bremsstrahlung from fast electrons produced by high-intensity photon bombardment of high-Z target (primary radiation source for OMEGA EP)

Radiation exposure limits
To protect people from any harmful effects, radiation exposure from other than natural sources is limited by law to the following:
Radiation worker exposure limit	5,000 mrem/year
General public exposure	100 mrem/year

Surface contamination
- Limit: 1,000 DPM/100 cm²
  Basis: Control spread of radioactive material, not exposure (continuous exposure to 10⁸ DPM/100cm² ⇒ 5 rem/yr)
Airborne limit
- Limit for radiation workers: 20 µCi/m³
  Basis: Exposure to this level for 2000 h/yr gives a dose of 5 rem
- Limit for general public: 0.1 µCi/m³
  Basis: Continuous exposure to this level will give an individual one half of their yearly limit of 100 mrem
Annual limit on intake (ALI):
- Limit: 80 mCi
  Basis: 5 rem

Natural radiation sources
Natural radiation sources and exposure levels are as follows:
Cosmic rays (from outer space)	45 mrem/year/person
Terrestrial (from natural minerals)	65 mrem/year/person
Internal (from elements in the body)	25 mrem/year/person

Radiation can damage individual cells by (if damage occurs slowly, it can be repaired as it happens)
- ionization of atoms within the cell
- free-radical formation within cell (e.g, H⁺ and OH^– )
- hydrogen peroxide poisoning of cell
- breakage of DNA strands
Genetic effects (studies indicate that the increased mutation rate due to most radiation doses is statistically insignificant)
- Damage to ova in ovaries
- Damage to sperm-forming cells
- Mutations of genetic material in ova or sperm
Effects on the organism
- Increased risk of ~2 cancers per 10,000 person rem of exposure assuming the linear model (less under threshold model) – compared to risk of 1,600 cancers per 10,000 from all other factors

Typical radiation doses
Dose	Source
4 mR/yr	Reading glossy magazines for 1 h/d from U and K
25 to 4,000 mR/yr	Wearing enameled jewelry 10 h/wk from U
100 to 200 mR/yr	Radon gas inhalation
100 to 200 mR/yr	Foods and fertilizers from K and U
100 mR/yr	Flying 5,000 miles per month
2,000 to 5,000 mR/yr	Smoking 1 pack of cigarettes/day From Po and Pb for U decay series

Effects
Dose	Effect
0 to 50 rem	No obvious effects, some blood chemistry changes
100 rem	Minor radiation sickness in about 10% of population
150 rem	Minor radiation sickness in about 25% of population
200 rem	Radiation sickness in about 50% of population
300 rem	Radiation sickness in all exposed, about 20% death rate within one month
450 rem	About 50% death rate without medical treatment
500 rem	Radiation sickness within 4 h, over 50% death rate
1000 rem	Radiation sickness in 1 to 2 h, 100% death rate