NU Class 7 Test flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- A1 versus A2
- A1 is the activity limit for special form material in a Type A package; A2 is the limit for other, normal-form material. Both values are tabulated per radionuclide, and A1 is often much larger.
- Special form material
- A non-dispersible solid radioactive source or sealed capsule that must pass impact, percussion and heat tests, allowing it to be carried in larger activities than normal-form material in the same package.
- Activity units becquerel
- One becquerel is one nuclear transformation per second. One curie equals 3.7 x 10^10 becquerel, so a millicurie corresponds to 37 megabecquerel of activity.
- Half-life decay formula
- Activity falls as A equals A0 times one half raised to t over the half-life. After seven half-lives about 0.8 percent of the original activity remains, which matters when planning shipments of short-lived isotopes.
- LSA and SCO material
- Low specific activity material and surface contaminated objects qualify for reduced packaging requirements. LSA is graded I to III and SCO into SCO-I and SCO-II according to contamination levels and dose rate.
- Fissile material and CSI
- Fissile nuclides such as uranium-233, uranium-235, plutonium-239 and plutonium-241 support a chain reaction. Their packages carry a criticality safety index, and consignments are limited by the summed index.
- Excepted package dose rate
- An excepted package of Class 7 material must not exceed 5 microsievert per hour at any external surface point, and its documentation and labelling requirements are simplified.
- Type A package
- A packaging designed to survive normal transport conditions and retain its contents. It requires no competent authority design approval and carries activity up to the A1 or A2 limit.
- Type B(U) and B(M)
- Type B packages survive accident conditions and carry high-activity contents. B(U) designs need unilateral approval from one competent authority; B(M) designs need multilateral approval from every country of transit or use.
- Type C package tests
- Type C packages used for high-activity air shipments must pass a 9 m drop onto an unyielding target, a crush test, an 800 degree Celsius fire for 60 minutes and a 200 m immersion test.
- Industrial packages IP-1 to IP-3
- IP-1, IP-2 and IP-3 industrial packages carry LSA and SCO material. IP-2 and IP-3 must also pass drop and stacking tests, with IP-3 adding a water spray test.
- Package identification mark
- The mark shows UN number, proper shipping name, package type designation, gross mass, country code, manufacturer and serial number, for example USA/9575/B(U)-96, so inspectors can match package to certificate.
- Surface contamination limits
- Removable contamination on package surfaces must not exceed 4 becquerel per square centimetre for beta, gamma and low-toxicity alpha emitters, or 0.4 for other alpha emitters such as plutonium.
- Category I-WHITE label
- Applied when the surface dose rate is at most 5 microsievert per hour and the transport index is zero. Only routine handling precautions are needed, with no special separation from film.
- Category II-YELLOW label
- Applied when the surface dose rate is at most 0.5 millisievert per hour and the transport index is at most 1. The label records radionuclide, activity, transport index and criticality safety index.
- Category III-YELLOW label
- Applied when the surface dose rate is at most 2 millisievert per hour and the transport index is at most 10. Values above these thresholds require exclusive use and special arrangement approval.
- Class 7 transport document
- Must state UN number, proper shipping name, class 7, radionuclide names, physical and chemical form, activity, category, transport index, criticality safety index and any competent authority certificate number.
- Class 7 vehicle placard
- Vehicles and freight containers carrying Class 7 material above excepted limits display a Class 7 trefoil placard plus an orange placard bearing the applicable UN number, such as UN 2912.
- Exclusive use statement
- The words Exclusive Use on the transport document mean one consignor only, supervised loading and unloading, and permission to use higher conveyance transport index and dose-rate limits.
- Radionuclide on the label
- Labels must list the radionuclide name, for example iridium-192 or molybdenum-99, and its activity in becquerels or multiples, so handlers can check the shipment against the transport document.
- Transport index definition
- The transport index is the maximum dose rate at one metre from the package surface in millisievert per hour multiplied by 100. A reading of 0.02 millisievert per hour gives index 2.
- Conveyance TI limit
- A vehicle or freight container normally carries a total transport index of no more than 50. Under exclusive use the limit rises to 200 and packages above index 10 are allowed.
- Exclusive use dose rates
- Under exclusive use the dose rate must not exceed 2 millisievert per hour at any point on the vehicle surface, nor 0.1 millisievert per hour at two metres from the vehicle.
- Fissile package spacing
- Consignments of fissile packages are arranged so the sum of criticality safety indices in any group is at most 50, with at least 6 metres separating one group from another.
- Segregation from undeveloped film
- Undeveloped film and mail bags are kept away from Class 7 packages by distances that grow with the transport index, Category III-YELLOW consignments requiring the greatest separation.
- On-deck stowage Class 7
- The IMDG Code generally stows Class 7 packages on deck, separated from accommodation spaces and from undeveloped film, with separation distances derived from the transport index.
- ALARA principle
- Doses are kept as low as reasonably achievable by combining time, distance and shielding. Halving exposure time halves the dose, while doubling distance cuts the dose rate to one quarter.
- Inverse square law
- Dose rate from a point source falls with the square of distance: doubling the distance reduces the dose rate to one quarter, the fastest practical way to lower exposure.
- Occupational dose limit
- The recommended limit for radiation workers is 20 millisievert per year averaged over five years, with no single year above 50 millisievert, and 1 millisievert per year for the public.
- Half-value layer
- The half-value layer is the shield thickness that halves the dose rate, calculated as 0.693 divided by the linear attenuation coefficient for that material and photon energy.
- Wipe test
- A wipe or smear test measures removable contamination by counting the activity picked up on an absorbent swab, indicating whether decontamination is needed before release.
- Damaged Class 7 package response
- Isolate the area, keep people upwind, avoid touching spilled material, allow no eating, drinking or smoking, notify the consignor and competent authority, then decontaminate with soap and water.