NS

1
NSE 619 Class 11

• Glass Finish Class 9 Theme
• Ceramics and Zeolites
• West Valley Demonstration Project
• Tritium
• Krypton 85
• Iodine
• Ruthenium

2
Ceramics

• Ceramics are man-made minerals
• Ceramics have specific chemical composition (each
  molecule must have the same elemental proportions
• One can either make the composition exact, or
  make a glass and then under pressure and
  temperature have the crystals grow out of the
  glass

3
Synroc

• Extracted from http//www.uic.com.au/nip21.htm
  Synroc is the most famous of ceramic waste forms
  (demonstrated in lab, but never used). See
  accompanying paper.
• Synroc can take various forms depending on its
  specific use and can be tailored to immobilise
  particular components in the HLW. The original
  form, Synroc-C, was intended mainly for the
  immobilisation of liquid HLW arising from the
  reprocessing of light water reactor fuel. The
  main minerals in Synroc-C are hollandite
  (BaAl2Ti6O16), zirconolite (CaZrTi2O7) and
  perovskite (CaTiO3). Zirconolite and perovskite
  are the major hosts for long-lived actinides such
  as plutonium (Pu), though perovskite is
  principally for strontium (Sr) and barium (Ba).
  Hollandite principally immobilises cesium (Cs),
  along with potassium (K), rubidium (Rb) and
  barium. Synroc-C can hold up to 30 HLW by weight.

4
Manufacturing Synroc

• Begin with TiO2, ZrO2, and Al2O3 (TZA)
• Produce a finely mixed sol
• Produce a spray dried powder with precise mixture
• Absorb waste on these powders
• Calcine
• HIP
• from p. 305, MRS Vol.333

5
Zeolites

• From February 20 lecture notes.
• See also second set of slides devoted just to
  zeolites

6
Zeolites

• Recall that zeolites were used as ion exchange
  media for Cs and Sr separation
• Naturally occurring mineral (First stage in
  hydrothermal decomposition of basalts)
• They are radiation resistant, survive for
  geologic times, trap both Cs and Sr, and have a
  composition similar to HLW.

7
Zeolites

• The zeolites are a popular group of minerals for
  collectors and an important group of minerals for
  industrial and other purposes. They combine
  rarity, beauty, complexity and unique crystal
  habits. Typically forming in the cavities, or
  vesicles, of volcanic rocks, zeolites are the
  result of very low grade metamorphism. Some form
  from subtle amounts of heat and pressure and can
  barely be called metamorphic while others are
  found in obviously metamorphic regimes. Zeolite
  crystals have been grown on board the space
  shuttle and are undergoing extensive research
  into their formation and unique properties.
• The zeolites are framework silicates consisting
  of interlocking tetrahedrons of SiO4 and AlO4.
  In order to be a zeolite the ratio (Si Al)/O
  must equal ½, i.e., twice as many oxygens as the
  combined Si and Al metal ions. The
  alumino-silicate structure is negatively charged
  and attracts the positive cations that reside
  within. Unlike most other tectosilicates,
  zeolites have large vacant spaces or cages in
  their structures that allow space for large
  cations such as sodium, potassium, barium and
  calcium and even relatively large molecules and
  cation groups such as water, ammonia, carbonate
  ions and nitrate ions. In the more useful
  zeolites, the spaces are interconnected and form
  long wide channels of varying sizes depending on
  the mineral. These channels allow the easy
  movement of the resident ions and molecules into
  and out of the structure. Zeolites are
  characterized by their ability to lose and absorb
  water without damage to their crystal structures.
  The large channels explain the consistent low
  specific gravity of these minerals.

8
Zeolites

• Natural ion exchange media
• They are a natural mineral formed from natural
  glasses
• Can be manufactured (? grown) at relatively low
  temperature
• Therefore, zeolites are an appealing candidate
  waste form
• Can easily be melted to form glass

9
Some Zeolite Minerals

• Scolecite CaAl2Si3O10 3H2O, Hydrated calcium
  aluminum silicate
• ChabaziteCaAl2Si4O12 6H2O, Hydrated calcium
  aluminum silicate
• Laumonite Ca4Al8 Si16O48 16H2O Hydrated calcium
  aluminum silicate
• Analcime NaAlSi2O6H2O, Hydrated sodium aluminum
  silicate
• Natrolite Na2Al2Si3O10 2H2O, Hydrated sodium
  aluminum silicate
• Stilbite NaCa2Al5Si13O36 14H2O, Hydrated sodium
  calcium aluminum silicate
• Heulandite (Ca, Na)2 - 3Al3(Al, Si)2Si13O36
  12H2O, Hydrated calcium sodium aluminum silicate
• Mesolite Na2Ca2Al6Si9O30 8H2O, Hydrated sodium
  calcium aluminum silicate
• Phillipsite KCaAl3Si5O16 6H2O, Hydrated
  potassium calcium aluminum silicate.
• Harmotome BaAl2Si6O16 6H2O, Hydrated barium
  aluminum silicate
• Check Analcime molecular weight 220, Na 23,
  so it is 10 Na

10
Observations

• All zeolites can have waters of hydration
• If the water is driven off, the zeolite may be
  transformed to a Feldspar (a German word for
  field rock, i.e., a common rock
• The most common feldspar is NaAlSi3O8, sodium
  aluminum silicate (8.8 Na)
• If a water is transformed to a hydroxl, OH-,
  probably with the loss of sodium also, the
  zeolite transforms to a clay, for example,
• Kaolinite Al2Si2O5(OH)4 aluminum silicate
  hydroxide

11
Observations Continued

• It is this interchange and relationship to long
  term natural analogues that make zeolites
  interesting for waste management
• If they pick up water they behave like clays
  which have a strong attraction for metal ions
• If they lose water they become more feldspathoid
  (rock like)
• They can just hold the water as zeolites, and
  remain geologically stable and a powerful ion
  exchange media

12
Synthesis of Zeolite

• Hundreds of zeolites have been synthesized
• Key points
• Temperatures less than 500 C, most often less
  than 200 C, some as low as 100 C
• Typical ingredients
• NaOH
• Silica Gel
• Diatomite
• Sodium silicate
• Clays and glass
• Water as steam
• Both calcium and sodium based zeolites have been
  prepared
• Well return to zeolites periodically

13
Resources for WV portion of lecture

• DOE/NE/44139-87, OPERATING EXPERIENCE DURING
  HIGH-LEVEL WASTE VITRIFICATION AT THE WEST VALLEY
  DEMONSTRATION PROJECT
• PNL-SA 25033. West Valley Full Scale Canister
  Impact Tests
• DOE/NE/44139-77,Vitrification Facility at West
  Valley
• DOE/NE/44139-73,Design of Equipment for HLW
  Vitrification Facility at West Valley
• DOE/NE/44139-75, Radiation Safety at West Valley
• DE-AR21-98FT4041-01, Tarzan A Remote Tool
  Deployment System
• For the West Valley Development Project
• DOE/EIS-0226-D, West Valley DEIS
• CONF-950232-32, Testing of the WV Transfer Cart
• Believe these are on the CD handed out

14
Facility Description and History

• Original and only Commercial Fuel Reprocessor in
  US
• Built by Jetty Oil in early 60s for 49 M
• Engineers were from ORNL, SRP and Hanford
• Operated in part on DOE fuel
• Closed in 72 by NRC for failure to comply
• Never reopened

15
History (cont)

• NRC license reverted liability to State of New
  York
• NY asked DOE to take over
• Clean up managed by DOE-ID with Westinghouse
  contractor (the key people came from Hanford FFTF)

16
(No Transcript)
17
Dr. Bs Contribution

• 1978-1980
• Inspect tank wall for corrosion
• Results
• Tank with waste, 180 F has no corrosion (lt10
  mils)
• Tank with no waste had severe pitting corrosion,
  (60 mil pits)
• 1989-1981
• Sludge removal studies
• 1983-1985
• Designed equipment to place risers on both tanks

18
Tank Risers

• Since one of the requirements was no new
  facilities, the decision was made to work within
  the tanks. However there was no access to the
  tanks except incidental pipes (4 altogether)
• By cutting holes into the tank roof and welding a
  32 in. steel pipe to the tank roof, one could
  hang equipment, up to 28 in. in diameter,
  bat-like, into the tank
• Since the tanks had massive internal columns,
  holes could be cut without compromising the roof
  load capacity.

19
(No Transcript)
20
Clean up Strategy

• Solidify 600,000 gal of neutralized HLW (vitrify)
• Convert LLW portion into a cementitious grout
• No New Facilities were to be built
• LLW, HLW, and SNF would be disposed of in
  accordance with 10 CFR 61 and 10 CFR 60

21
Vitrification

• PNNL designed and built the glass melter
• Neutralized HLW had sat for 20 years without
  being disturbed high degree of separation of all
  FP but Cs in the sludge and Cs in the supernate
• Cs was separated from the supernate on zeolite
  resin, resin added to sludge, and resin plus
  sludge was washed and vitrified
• Supernate minus Cs was grouted
• About 250 canisters (10 ft high by 2 ft diameter,
  Yucca Mt canisters) were made.

22
Estimated cost

• 100 M/y since 1983
• Approximately 2.5 B project, with Glass yet to
  be shipped and disposed of.
• Disposal, at 750 K/m3 250 canisters 200 M
• Operational costs
• 1.2 M/glass canister
• 5,500/cubic meter for cementitious grout

23
From a presentation by Mike Lawrence, Head of
DOE-Rl in 11/1999
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
Tritium

• The amount of tritium is a function of fuel
  make-up, reactor purpose, and presence of lithium
  in the reactor or fuel
• Source of tritium
• Fission
• 6Li(n, a )
• Fission A 1000 Mwe reactor has 0.12 failed
  fuel (all of the tritium in a failed element is
  released) and loses about 26 Ci/y, old data from
  a BWR safety analysis.

28
Tritium, cont.

• For purposes of this example, assume the reactor
  has 100 tons fuel, and releases 26 Ci H-3 per
  year.
• Therefore, it must produce 26/0.0012
  approximately 21,000 Ci/y or 0.2 Ci/kg of fuel.
• The US has about 90 MWe operating (continuously)
  Therefore, we should generate about
• 1.89 MCi(H-3)/y
• IDB (1994) gives 1.6 MCi/y

29
Tritium, cont.

• H-3 Specific Activity 9,650 Ci/g
• IDB Reference PWR fuel assembly 3.85 m long,
  3.66 m fuel, 0.95 cm O.D., 264 rods/assembly, 461
  kg U (heavy metal)/assembly
• U per fuel rod 2 kg
• Therefore a fuel rod has about 0.4 Ci or 4E-5 g
  of tritium
• The point is?
• Relative to reprocessing any fuel there are not
  insignificant quantities of H-3 present. It will
  distribute in both the liquid and the offgas.
  All HLW liquid will contain HOT water. It must
  be dealt with.
• At 450 liter (HLW)/ton HM, liquid HLW will have
  about 200 Ci tritium or 0.5 Ci/l

30
Fuel computations
31
Krypton 85

• What about Krypton?
• From Chart of Nuclides, 1.32 of fission products
  are m 85 and about 80 of these end up as Kr-85
  with a 10.76 yr half-life
• If you are reprocessing fuel, 99.88 of this is
  still in the fuel.
• It will be freed and since it is a noble gas, it
  will go off with the offgas. To date that is
  what has happened to all Kr-85 in reprocessed
  fuel.

32
Krypton-85, cont.

• Now suppose that reprocessing becomes acceptable
  and the United States began reprocessing for 200
  reactors (40 electrical energy) That is 30 t/y
  200 or 6000 mt HM/y. At 3 burnup, this is
• Remember 1 kg U-235 gt 1 kg fp, but is a number
  basis
• 60001000 kg 0.030.0132(85/235)0.8 470 kg
  Kr-85
• At 392 Ci/g, this is 184 MCi/y probably too much
  to release to the environment

33
Alternatives for Kr-85

• As a noble gas, one can
• a) leave it in the fuel (dispose of it with the
  SNF)
• b) release it to the atmosphere
• c) capture it in chilled activated carbon beds
  and then move it to tanks and store under
  pressure (proposed, never done)
• d) INEEL worked on a process to condense it in a
  powdered zeolite matrix, then, under high
  pressure and temperature, sinter it into a solid,
  which retains most of the Kr process known as
  HIP(ing) (Hot Isostatic Pressure)

34
Iodine

• There are two major iodine isotopes
• I-129 (1.57E7 y half life) a performance limiting
  isotope since it is longer than geologic times
  and is very soluble, i.e., mobile.
• I-131 (8 day half life) of interest in reactor
  accidents, since its fission yield 2.5, a beta
  emitter, volatile, and soluble.
• Only I-129 is a waste management issue

35
Ruthenium

• Ru-103 (fission yield 3) 39 day half life
• Ru-106 (fission yield 0.4) 1 yr half life
• Strange semi-noble metal with volatile oxides
• Ruthenium Tetroxide, 0.5 Stabilized Aqueous
  Solution in Crystal form RuO4   F.W. 165.70  
  CAS 20427-56-96m.p. 25.4C, b.p. 40C
• Filtration/offgas problem for first 10 years.