8/12/2019 2 - Blue Topaz

1/28

8/12/2019 2 - Blue Topaz

2/28

Composition is Al2SiO4(F,OH)2 Will also have trace impurities that vary from

location to location

These impurities can affect color and activationproducts

Pure topaz is colorless or pale yellow

Blue topaz can occur naturally, but is usuallyproduced via irradiation

8/12/2019 2 - Blue Topaz

3/28

Reactor-irradiated, using neutrons

Produces Swiss blue (a deep blue)

Accelerator-irradiated, using electrons

Produces London blue or sky blue (a lightershade of blue)

Gamma-irradiated, using Cs-137

Also produces London blue and sky blue

8/12/2019 2 - Blue Topaz

4/28

Mineral color is a result of physical structure

(e.g. opal) and/or the interactions of light withelectric fields in a mineral

Exposure to ionizing radiation can alter a

minerals distribution of electric charge Exposure to particle radiation (especially large

particles) can also change a crystals physical

structure Impurities can also affect color by stressing the

crystal structure and influencing electron

configuration

8/12/2019 2 - Blue Topaz

5/28

8/12/2019 2 - Blue Topaz

6/28

Neutron irradiation produces a deeper blue

than irradiation by gammas or electronsbecause

Neutrons are more heavily ionizing,

Neutrons induce more change to the crystalstructure

Neutrons penetrate the whole crystal (unlike

electrons)

8/12/2019 2 - Blue Topaz

7/28

8/12/2019 2 - Blue Topaz

8/28

Radiation safety

Contamination Radionuclide concentrations and doses

Health and safety

Dose to end users

Dose to workers

Regulatory compliance Possession (state)

Exempt distribution (NRC)

8/12/2019 2 - Blue Topaz

9/28

8/12/2019 2 - Blue Topaz

10/28

Most stones are cut and polished prior to

irradiation NO stones are cut or polished by PAJ

In addition, any items that are to be

electroplated must be rigorously cleaned toensure proper adhesion of electroplated metals.

Accordingly, there should be no contamination This should be checked by manufacturer, prior to

shipping

8/12/2019 2 - Blue Topaz

11/28

These will vary, depending on the impurities(activation targets) and neutron fluence

Nuclide Half-

life

(days)

Exempt /

expected

concentration

(nCi/gm)

Maximum /

expected nuclide

concentration on

receipt

(3 weeks post-

irradiation)

Maximum / expected

nuclide concentration at

time of transfer to non-

licensed customer

(6 weeks post-irradiation)

Sc-46 84 0.40 0.07 0.34 0.059 0.28 0.050Mn-54 312 3 0.05 2.9 0.048 2.7 0.046

Zn-65 244 3 0.05 2.8 0.047 2.6 0.044

Cs-134 752 0.09 0.02 0.088 0.02 0.087 0.019

Ta-182 115 0.4 0.2 0.35 0.18 0.31 0.16

8/12/2019 2 - Blue Topaz

12/28

Nuclide Half-life

(d)

Radiation

emitted

(mR/hr per

Ci at 30 cm)

Expected activity in

one item of jewelry

(Ci)

Sc-46 84

0.013 0.00048

Mn-54 312 0.0057 0.0036

Zn-65 244 0.0037 0.0036

Cs-134 752

0.011 0.00011

Ta-182 115

0.0086 0.00048

Total 0.00827

Integrated 1-year radiation dose

On contact with skin

(Varskin 3)

At a distance of 4 cm

(MicroShield)

Scenario

shallow deep shallow deep

Exemption limits (worst

case)

3700 mR 388 mR 137 mR 24 mR

Expected concentrations 760 mR 29 mR 34 mR 1.8 mR

8/12/2019 2 - Blue Topaz

13/28

No contamination is expected

Radionuclide concentrations will likely be onlya fraction of exempt concentrations

Radiation dose and dose rates expected to be

low, even for large quantities of gemstones May have over 500 kg of irradiated gemstones on-

hand at any given time, and more before holidays

(Christmas, Valentines Day, Mothers Day)

8/12/2019 2 - Blue Topaz

14/28

8/12/2019 2 - Blue Topaz

15/28

8/12/2019 2 - Blue Topaz

16/28

8/12/2019 2 - Blue Topaz

17/28

Not from radiation

8/12/2019 2 - Blue Topaz

18/28

8/12/2019 2 - Blue Topaz

19/28

NRC guidance documents date back about 20

years, and assume that gems will be irradiatedin the US

In reality, gems are now irradiated overseas

and undergo considerable decay beforeimportation

Much of the NRC licensing guidance isappropriate; some is not

8/12/2019 2 - Blue Topaz

20/28

The purpose of the NRC license is to import

gems, characterize the radionuclideconcentrations (hopefully less than exemptionlimits), and then distribute as exempt

radioactive materials This means that the licensee must be able to

show that they are capable of performing

receipt surveys and (more difficult) determinethe radionuclide concentration in these gems

8/12/2019 2 - Blue Topaz

21/28

8/12/2019 2 - Blue Topaz

22/28

The day I visited, two pallets of earrings

arrived Each pallet held 20 boxes

Each box contained over 200 cards, each with 5

sets of earrings Only 1 set per card contained blue topaz

Other packages may contain up to 10,000bracelets, each with 6 stones

Surveying every individual item is

prohibitively time-consuming

8/12/2019 2 - Blue Topaz

23/28

Need to be able to demonstrate that hot gems

do not escape detection Need to be able to demonstrate that gems do

not exceed exempt concentrations for any

nuclides (the sum of fractions rule applies) Need to demonstrate that the licensee can make

these determinations to the satisfaction ofregulators

8/12/2019 2 - Blue Topaz

24/28

Must be able to show that the licensee can

safely possess and secure radioactive materials Total activity is less than that of most soil

density gauges, so this is not difficult

8/12/2019 2 - Blue Topaz

25/28

8/12/2019 2 - Blue Topaz

26/28

The packaging

area too manypeople (and toolittle dose) to be

rad workers.

Receive packages,

awaiting surveying

8/12/2019 2 - Blue Topaz

27/28

8/12/2019 2 - Blue Topaz

28/28

Topaz (and some other gems) may be

irradiated to cause it to change color Irradiation can induce radioactivity, albeit in

exempt concentrations

Irradiated gems exhibit only low levels ofradiation and do not pose a health risk

Prospective licensees must be able to convincethe regulators that they are competent todetermine that gems are exempt from

regulation