Disposal and Transportation of High Level and Transuranic Waste and Emergency Preparedness

Matthew Vining SYE 4503

High Level Waste 1. By-products and remnants of the reprocessing operation 2. Used Nuclear Fuel (UNF) 3. Other materials that may be defined as HLW by the NRC

Transuranic Waste • Man-made isotopes with an atomic number Z > 92 (Uranium) • Half-life longer than 5 years (NRC) – EPA and DOE use 20 years • Concentration greater than 100 nCi/g of waste.

• The U.S. is the only country which defines TRU. Other countries treat TRU as HLW

Transuranic Waste • Examples: glove boxes, filters, tools, and chemical sludges produced by Pu recovery streams • Bulk of TRU generated by DOE (defense using Pu separation) • In general, contains isotopes of Np, Pu, Am, Cm, and Cf

Production of HLW and TRU (Conca, 2013)

Types of TRU • Contact-handled (CH) TRU – does not require remote handling because most radioactivity comes from alpha particles (doesn’t penetrate package) • Remotely-handled (RH) TRU – emits enough gamma rays, neutrons, and betas to require special precautions – ~1% of TRU

Disposal of TRU • Before 1970 – buried in shallow pits and trenches at both government-owned and commercial sites. • 1970 and after – U.S. decided TRU required better containment and started storing TRU

Danger of TRU • Due to alphas, TRU is harmful if ingested or inhaled (high dose rate in small volume) • Z > 92 → if inhaled heavy metals; If ingested, relatively small fraction absorbed in digestive tract. → Much more dangerous

Disposal of HLW • Prevalent idea is to solidify liquid waste and place in geological repository (Conceptual Design of Yucca Mountain Disposal Plan , 2012)

Solidification of HLW 1. Calcination – Waste heated up to point that it becomes completely dry. Leaves powder-like substance.

2. Cementation – Liquid waste mixed with cement and poured into container where it is allowed to dry into a concrete block.

Solidification of HLW 3. Vitrification – Waste mixed with glass frit to form solid glass which contains waste in solid solution.

Preferred method

because of advantages offered by glass.

Vitrification (What is a canister of HLW?, 1998)

Vitrification Methods • Slurry-Fed Ceramic Melter – Method used in U.S.

– Slurry fed into melter with frit • AVM – Method Used in France and most other countries – Waste calcinated then mixed with glass frit in melter

Ideal Material vs. Glass

Ideal Containment Material

Retain, in insoluble form, all fission products and other chemical elements contained in liquids from used fuel reprocessing Have suitable mechanical properties

Glass

Low leach rate and low solubility in water High solubility for nuclides found in HLW and TRU Shows resistance to radiation damage Stable properties over thousands of years A material with which man has considerable experience over thousands of years => Reasonable to assume that glass specially designed will last at least that long Be relatively inexpensive and easy to handle Requires moderate temp for preparation

Vitrified Glass (How is radioactive waste managed now - High Level Waste (HLW), 2010)

Vitrification Facilities in U.S.

• West Valley Demonstration Project (WVDP) - West Valley, NY – Currently being decommissioned • Defense Waste Processing Facility at Savannah River Site – Aiken, SC • Hanford Waste Treatment and Immobilization Plant – Hanford, WA – Under construction

Disposal Objectives • Protection of the environment for both current and future generations • Protection of people for both current and future generations • Note: Protection doesn’t imply zero risk but rather acceptable risk (as determined by society responsible for waste)

Dispersal • Dispersal – The deliberate release of radioactive materials to the environment, controlling both the rate and the amount released, and its subsequent dilution by the air and water of the earth to concentrations that are considered safe. (345, Tsoulfanidis) – Practiced by industry but limited to release of small amounts of activity and few selected isotopes

Containment • Containment – Placing wastes behind one or more barriers to ensure their isolation from the biosphere for as long as it is considered necessary. (345, Tsoulfanidis) – Potential environmental impact must be considered – During period when site is in use – retrieval of waste possible – After site is closed – retrieval not possible and monitoring of site not necessary

Reversibility & Retrievability • Reversibility – reverse or reconsider decisions • Retrievability possible if location known • Advantages – Cost of retrieval reduced – It will put the minds of skeptics at ease (if mistake occurs, waste is retrievable) – Additional: Future generations may find use for waste

Disposal Methods • Deep geological disposal – Yucca Mountain • Ice sheet disposal • Outer space disposal • Sub-seabed disposal • Seabed disposal • Deep boreholes Ice Sheet Disposal

Transmutation • Reactors used to bombard long half-life radioisotopes with neutrons or protons to transmutate them into stable isotopes or into radioisotope with shorter half lives.

– Occurs in breeder reactors when burning Plutonium • Resources and money saved in treatment and handling of HLW

Accelerator-Driven Systems • Accelerator (most likely proton) will generate neutrons by hitting metal targets • Neutrons cause transmutation in most of the fissionable materials (blanketed by metal target) • System remains subcritical, but produces enough heat to generate electricity

Geological Repository Features • Similar to a mine (600 – 1200 m deep) • Retrievable for 50 – 100 years • 3 barriers to isolate waste – Geological medium of repository – see Table 9.12 (351) for materials – Metal canister – expected to corrode in ~ 300 years – Waste form – glass or ceramic (vitrification)

Geological Repository Safety • For contamination - Water must penetrate host rock (selected due to lack of water), move through crushed rock, move through overpack (probably steel or titanium cylinder), into glass or ceramic, and back through all previous barriers

Geological Repository Safety

Geological Material Properties

Geological Repository Concerns • Safety still questioned due to lack of experimentation; However, naturally occurring reactor in Oklo, Gabon in West Africa effectively contained the ~ 10 tons of HLW it produced within the ore and occurred naturally (not engineered)

WIPP • “The Waste Isolation Pilot Plant (WIPP) is a project undertaken by the DOE (with congressional authorization) for the purpose of providing a research and development facility to demonstrate the safe disposal of radioactive wastes resulting from the defense activities of the United States, primarily TRU waste.” • Exempt from NRC regulation

WIPP • Similar to geological repository using bedded salt • Uses

in situ

testing • During pilot phase, all wastes retrievable • As of 2011, many rooms successfully filled with TRU and opening closed with concrete blocks

Transportation Regulations • Regulations related to transportation issued by 3 federal agencies in U.S.

– U.S. Department of Transportation (DOT) – 49 CFR 100-177 & 49 CFR 178-199 – NRC – 10 CFR 71 – U.S. Postal Service – 39 CFR 124 • Regulations do not differentiate between LLW and HLW • Criteria to ship based on activity and isotopes contained

Transportation Regulations • International Atomic Energy Agency (IAEA) – established regulations which formed basis of most international agreements related to transportation • U.S. has over 50 years of experience and no member of public has currently been injured by radioactivity

DOT • Regulates the transportation of nuclear material, transportation routes, and helps set standards for nuclear packaging • Works in conjunction with affected states, international agencies, etc.

U.S. NRC • Regulates the design, manufacture, use, and maintenance of containers for high level radioactive shipments.

• Regulates packaging of UNF

U.S. Postal Service • Regulates packaging, labeling, and mailing of radioactive materials.

Definitions and Classification • Based on 10 CFR 71 January 2010 revision (applies to both LLW and HLW) • Type A package: •

Shipper Responsibilities 1. Select proper packaging.

2. Check materials license of the recipient. (Does it allow the material being shipped?) 3. Use correct labels.

4. Check package for external (surface) contamination.

5. Check radiation levels on the outside of the package.

Recipient Responsibilities 1. Check shipping papers. (Is this what was ordered?) 2. Are contents allowed (covered) by your license?

3. Check package for external (surface) contamination.

4. Check radiation levels on the outside of the package.

5. Check contents after package is opened. (Is this what was ordered?)

UNF Shipping Casks Tests (NRC staff, 2012)

Sandia National Lab • Transportation Technology Center at Sandia National Laboratories (SNL) in Albuquerque, NM • Full–scale tests (with new cask design) to verify computer models of cask damage in accidents • http://www.sandia.gov/tp/SAFE_RAM/SEVERITY.H

TM • Tests seemed to verify computer models

Sandia National Lab • Scientist also simulated terrorist attacks using explosive devices – Highly unlikely due to: • Weight of cask (couldn’t remove from carrying vehicle) – Lighter casks for truck usually between 25 and 40 tons – Heavier casks for rail up to 120 tons • Weight of plug (hard to remove; several tons) • If plug removed, radioactivity would cause lethal dose

Holtec Missile Impact Test

UNF Generic Shipping Casks (NRC staff, 2012)

Cask Cross Section (NRC staff, 2012)

Cask Radiation Limits • Not more than 2 mSv/h at any point on surface of cask • Dose rate of not more than 0.10 mSv/h at any point 2 m away from cask boundary • Dose rate of not more than 0.02 mSv/h at any normally occupied position (seat of truck, etc.)

Emergency Preparedness • Federal Emergency Management Agency (FEMA) – Responsible for federal response to any disaster, including nuclear related – Developed procedures and guidelines to handle radiological emergency – Chair of Federal Radiological Preparedness Coordinating Committee (FRPCC) • Made of 20 federal departments and agencies • Develops policies and procedures for radiological preparedness and response

Emergency Preparedness • DOT – provides materials to states for training of fire, police, and ambulance personnel • DOE – 8 offices for radiological assistance

Emergency Preparedness • States – State Emergency Management Agency (SEMA) • Institute of Nuclear Power Operations – voluntary assistance agreement among electrical utilities which will assist each other in cases of radioactive materials transportation accidents

Thank You Questions?