1. Power Generation and Spent Fuel
Sources of Radiation
Nuclear Fuel Cycle –
Power Generation and Spent Fuel
Day 4 – Lecture 8(1)

2. Power Generation
Power Generation has already been discussed under Nuclear Reactors

3. Spent Fuel

4. What is the “Back End” of the Fuel Cycle
The back end has to do with post-reactor use of the (now) irradiated fuel
Irradiated fuel is extremely radioactive and generates heat
Clouded by politics, policy issues, national pride, NIMBY, BANANA, LULU etc.
Issue defused by excellent power plant records, longer fuel burnups, compact nature of waste
Economics clouded
No clear route driven by safety
NIMBY = Not In My Back Yard
BANANA = Build Absolutely Nothing Anywhere Near Anybody
LULU = Local Undesirable Land Use

5. Unirradiated fuel
Minimal Radiation Hazard

6. Irradiated Fuel SNF being moved during refueling
High Radiation Hazard - No people nearby

7. Irradiated/SNF options
storage
wet or dry
at reactor or away
reprocessing
wet schemes - Purex
dry schemes
transmutation
disposal
repository/geologic
SNF
HLW

8. Spent Fuel
With time, the concentration of fission fragments and heavy elements formed in a fuel bundle will increase to the point where it is no longer practical to continue to use the fuel. So after 12‑24 months the 'spent fuel' is removed from the reactor.
When removed from a reactor, a fuel bundle will be emitting both radiation, principally from the fission fragments, and heat. Spent fuel is unloaded into a storage pond immediately adjacent to the reactor to allow the radiation levels to decrease. In the ponds the water shields the radiation and absorbs the heat. Spent fuel can be stored safely in these ponds for long periods.
Depending on policies in particular countries, some spent fuel may be transferred to central storage facilities. Ultimately, spent fuel must either be reprocessed or prepared for permanent disposal.

9. Example: Wet Storage Of SNF
Closeup
La Hague,
France
Side View
* One of five large SNF storage pools at the Cap de la Hague Plant (Cogema) in France.
* Total capacity of all pools at La Hague circa 13,000 MTHM.
* Total LWR capacity at BNFL Sellafield/THORP Plant around 3,500 MTHM.
* Typical reactor pool is much smaller and has a lower capacity of around 500 MTHM or so.
End View

10. Above Ground Dry Storage
It can also be dry stored in engineered facilities. However, both kinds of storage are intended only as an interim step before the spent fuel is either reprocessed or sent to final disposal. The longer it is stored, the easier it is to handle, due to decay of radioactivity.
There are two alternatives for spent fuel:
reprocessing to recover the usable portion of it
long‑term storage and final disposal without reprocessing

11. Dry Storage - Internals
24 assemblies PWR
24 KW max. (typical)
* Early designs were all stainless steel.
* More recent designs are coated carbon steel (cost and machining savings). There were some initial problems with the coatings failing and the generation of hydrogen gas.
* Basket material can be boron/stainless steel alloy.
* This is the inner container and basket. After sealing (by welding a top on), it would be placed in a transfer container and then into one of the concrete storage modules.

12. SNF Dry Cask Transport
* Movement of inner basket in a site vertical cask at the Surry Plant.

13. Nuclear Power Reactor Spent Fuel Waste Management
Country Policy Facilities
Finland Direct Disposal Spent fuel storage in operation - Five sites located for deep repository, one to be selected in 2010 for use by 2020
France Reprocessing Two facilities for storage of short- lived wastes - Site selection studies underway for deep repository for commissioning 2020
United Kingdom Reprocessing Low-level waste repository in operation since High-level waste currently vitrified and stored, new underground repository planned
USA Direct Disposal Three low-level waste sites in operation - Investigations on national final repository at Yucca Mountain
Here are some examples of some countries on policy of spent fuel waste management and the facilities for that

14. Reference
International Atomic Energy Agency, Postgraduate Educational Course in Radiation Protection and the Safety of Radiation Sources (PGEC), Training Course Series 18, IAEA, Vienna (2002)