NS

1
NSE HLW - Class 2

• Review spent fuel statistics and data from IDB
• Review HLW statistics and data from IDB
• Review 10 CFR 60 regulations on
• SF-HLW disposal
• HLW performance criteria, and material
  qualification procedures.
• HLW Repository WAC

2
SF Statistics from (Rev. 13) IDB

• Note If you have a different Rev, 11, 12, or 13,
  the table numbers will be different, but the data
  will be almost the same
• 107 reactors Fig 1.1 (Rev. 11) with a P 98 Gwe
  Fig. 1.1 (Rev. 13)
• Activity and power for 30,000 MWD/MTIHM (PWR)
  (Fig. 1.5 Rev. 11)
• Activity -1-2 MCi initially 0.1 MCi after 100
  years
• Power 8 0.5 kW first 100 years

3
SF StatisticsFrom Rev 13 IDB

• Approximately 47,000 MTIHM (Figure 1.3)
• Discharge rate - 2000 t/y for 100 reactors
• Dimensions - Table 1.4
• Fuel bundle (assembly) is 0.25 to 0.5 tonne HM
• Reference DOE SF Table 1-5
• 5700 MTHM, most of which is at Hanford (but low
  burn-up relative to commercial fuel.)

4
Observe heat and radiation levels

• Radiation - use 1 (R/h) (m2 /Ci), i.e., at 1 m, 1
  Ci of 1MeV gamma emitter will produce a field of
  1 R/h
• 0.1 M Ci --gt 105 R/h at 1 meter
• (For humans, 200 mR/h is close to limit 400 rem
  is the LD50 for materials, plastics fail at 106
  107 rad
• although not technically accurate, 1 R 1 rem 1
  rad
• Heat 1 kW can produce centerline temperatures of
  300 700 C depending on heat conductivity and
  canister.

5
Radiolysis

• Classically measured as G value
• G number of atoms (or molecules) produced per
  100 eV
• Values like 0.1 - 2 are typical
• Note since typically energy loss is 35 eV/ion
  pair
• G 1 implies a conversion rate (ion pair leading
  to chemical reconfiguration) of 30
• simplest case is H2O (liquid) dissociating to H2
  (gas) this process goes through intermediate
  steps of H2O, H2O-, OH-, (see
  http//www.mun.ca/biology/scarr/Radiolysis_of_Wate
  r.htm )

6
High-level Liquid Waste HLLW

• Details of the Pu/U separation will be addressed
  next week by Vince Maio
• Most commercial fuel is UO2 (sometimes written as
  U2O4 a black ceramic with a density of about 11
  g/cc http//www.webelements.com/webelements/compou
  nds/text/U/O2U1-1344576.html see
  http//www.unitednuclear.com/pellet.htm for a
  picture). Weapons production and some others use
  metallic fuel. The fuel is contained in
  stainless steel (FFTF), Al, or zirconium alloy
  (commercial) tubing.
• Recall that after it has burned up it may be
  0.5 fp to 4 fp (commercial) or higher
  (submarine fuel).
• Dissolving the fuel may include the tubing (hull)
  or may be just the Uranium/uranium dioxide.

7
Dissolving Fuel

• The objective it to put the metal or oxide in
  solution with minimal added material
• Nitric Acid, HNO3, has universally been the
  choice concentrated and boiling see
• http//www.uic.com.au/uicchem.htm or
  http//www.chem.ox.ac.uk/icl/heyes/LanthAct/A10.ht
  ml for chemistry of Uranium
• 2HNO3 U 2 H2O gt UO2 (NO3)2 3H2
• or 2HNO3 UO2 gt UO2(NO3)2 2H2
• Uranyl Nitrate is soluble in boiling water at
  gt600 g/l http//www.laddresearch.com/wsmsds/21397.
  htm

8
Purex Flow Sheet
9
A Dissolver used at Hanford
Purex Dissolver 24 ft tall, 9 ft in diameter, 10
tons, steam heated. About a 1000 lbs of fuel was
dumped in the top and dissolved.
10
Look at Volumes and Densities

• Consider 1 ton of spent UO2 fuel with a 4
  burn-up 1000 kg U, 40 kg of U-235 converted to
  fission products
• Initial Fuel was 235 g U 32 g O2, or 267 g/mole
• 1000 kg HM has a mass of (267/235)1000 1136 kg
• Density of 11 g/cc or 11 kg/l it had a volume of
  100 liters
• It dissolves to UO2(NO3)2 which has 235 g of
  U/mole and a mass of 235 816 228 391
  g/mole
• Since you can dissolve about (600/391)235 360
  g U/liter aqueous solution

11
Volumes and Densities, cont.

• Therefore it will take (1000/0.360) 2800 liters
  to dissolve a ton of fuel. However, once you
  extract the HM (U and P) then you only have 40 kg
  of fission products, and at 100 g/l, you should
  be able to have all of the remaining fission
  products in about 400 l of aqueous solution (a
  reprocessing article quotes 450 l/MTHM)
• The actual concentration will probably be
  dictated by the thermal heat which is high enough
  to produce boiling.
• The 40 kg of fission products, have an average
  atomic mass of (90 140)/2 115, and most form
  dioxides, so as dried oxides, they would have an
  atomic mass of 147, so the 40 kg of fp would have
  a mass of (including the oxides) of 40147/115
  51 kg of oxides.

12
Volumes and Densities, cont.

• The fission product oxides typically have a
  density of 1 - 2 kg/l (dry solids or dry
  crystals), so we end up with 20 to 40 liters of
  fission products (note that many of these will be
  non-radioactive by the time you measure them.
  But there are more than 10 of the fission
  products which are noble gasses (Kr and Xe) so
  the actual number is a little less.
  Nevertheless, with concentrated nitric acid in
  steel vessels, there will be almost as much iron,
  nickel, chromium, and whatever came along from
  the fuel tubing, also.
• Part of the point of this analysis is to make it
  clear to you that the fission products are a
  significant mass and volume of the actual HLW.
• And, the bottom line is that aqueous HLW in its
  concentrated form is about 400 to 500 liters per
  ton HM

13
HLW from Reprocessed SF

• Figure 2.1 ff.
• Volume - 300,000 m3 -- this is 10x that of
  Commercial SF
• Note that form the 500 liters per ton, you might
  guess that we reprocessed 300,000 MTHM in
  manufacturing weapons. However it varies as high
  as 3000 l/ton http//www.world-nuclear.org/uiabs93
  /ricaud.htm
• Activity - 1 GCi compared to 27 GCi for
  Commercial SF (GCi 109 Ci)
• HLW composition - see Table 2.11 Hanford Waste
• And Table 2.13 SRS Waste

14
Plutonium Production

• From http//www.osti.gov/html/osti/opennet/documen
  t/pu50yrs/pu50yc.html
• The total DOE plutonium acquisitions for the
  period 1944 to September 30, 1994, were 111.4
  metric tons. Of the 111.4 MT plutonium acquired,
  104 MT were produced in Government reactors
  103.4 MT in production reactors, and 0.6 MT in
  nonproduction reactors. In addition, 1.7 MT were
  acquired from U.S. civilian industry, and 5.7 MT
  from foreign countries. This section describes
  each of the acquisition categories in detail.
• The Weapons Production Reactors operated at
  slight enrichment and dissolved most of the fuel
  hulls. Therefore it did take somewhere between
  100 and 300 thousand tons to produce this Pu, and
  result in 300,000 m3 of waste. So our
  calculations are reasonable.

15
Composition

• Counting Tank, Glass, and Capsule wastes
• Hanford - 15 isotopes account for 413 MCi
• SRS - 20 isotopes account for 481 MCi
• Of those activities Sr-90/Y-90 plus
  Cs-137/Ba-137m account for 411 and 478 MCi
  respectively
• Therefore, for radiation estimation purposes, one
  can assume that after a few years, all
  radionuclides are Cs and the Sr pairs, with an
  error of 0.5, with all of the penetrating gamma
  radiation arising from Ba-137m (of course this
  depends upon your objective.)
• The remaining long-term hazards are attributable
  to Am, Np, Pu, U, I and Tc.

16
Review of 10 CFR 60

• Section 60.1, 60.2 Purpose and Definitions
• Section 60.21(c)(5) Need waste description
• Section 60.43 (b) Restrictions on waste
• Section 60.101 Technical Criteria, ff
• Section 60.111 Performance Objectives, ff
• Section 60.113 Barrier Performance, ff
• Section 60.122 Siting Criteria, ff
• Section 60.135 Waste Package, ff

17
Repository Regulations

• Note the regulations are clearly safety based.
• 10 CFR 60.42 necessary to protect health and
  safety and environmental values
• 10 CFR 60.101 will not constitute unreasonable
  risk to health and safety
• 10 CFR 60.111 meet 10 CFR 20
• 10 CFR 60.113 - Performance objectives (see next
  slide) 50 y retrievability
• 10 CFR 60.135 - Waste Package Criteria

18
The Solution

• Deep (gt300 m) Geologic Disposal
• 10,000 -100,000 year confinement (release rate
  from engineered barrier ), 1 part per 100,000
  per yr.
• Allocate first 1000 years to waste container
  containment substantially complete
• Next 10,000 years to Waste Form
• Next 100,000 years to Geologic Media

19
Waste Package Criteria

• Cant compromise the geologic setting or
  underground facility
• Must consider
• solubility, oxidation-reduction, corrosion,
  hydriding, gas generation, thermal effects,
  radiolysis,radiation damage, leaching, fire and
  explosion, and thermal
• No explosives, pyrophorics, free liquids, shall
  be solid and sealed, no particulates,
  noncombustible, plus Others(!)

20
Stable Man-Made Materials

• Glass
• Bricks
• Hydraulic Cements

21
What can meet these requirements?

• Look at geologically stable materials

22
The Problem

• Transuranics (Np, Pu, Am, Cm) and Actinides (Ac,
  Th, Pa, U plus TRU)
• Long-lived beta/gamma emitters
• Ultimately dominated by Actinides Am(241 and
  243), Pu(239 and 240), and Np-237
• and, Fission and Activation products I-129,
  Tc-99, C-14, Nb-94

23
The Problem, cont.

• First 1000 years, HLW has both high Radiation and
  Thermal
• Radiation is high enough to cause material
  damage dislocations, embrittlement, stored
  energy, degradation of polymers, radiolysis
• Thermal implies there is enough heat to raise
  temperatures to 700 - 800 C
• After 1000 yr, HLW equivalent to TRU

24
The Solution

• Deep Geologic Disposal (see 10 CFR 60)
• 10,000 -100,000 year confinement
• Allocate first 1000 years to Waste Container
• Next 10,000 years to Waste Form
• Next 100,000 years to Geologic Media
• 10 CFR 63 changed this to less than one chance in
  10,000 over 10,000 years that Performance Goals
  will be exceeded

25
10 CFR 63

• See file Named Key Items in 10 CFR 63 (also read
  10 CFR 63)
• 10 CFR 63 is Yucca Mtn specific
• It allocates everything to the license which
  allocates containment assurance to design and the
  performance assessment
• Does not place requirements on the waste form
• Waste form requirements contained in the Waste
  Acceptance Criteria Document

26
Current HLW Repository WAC

• Vitrified waste is specified as the standard HLW
  form that passes the Product Consistency Test,
  or equivalent
• The PCT leachate shall be less than those of the
  benchmark glass
• Observe, that HLW Repository WAC have to meet the
  10 CFR 60 requirements, but do not have to equal
  them.
• Recent version of HLW WAC has deleted even
  reference to 10 CFR 60, instead have been
  referred back to Nuclear Waste Policy Act
• No RCRA regulated wastes accepted
• These last two essentially require a 2-ft
  diameter glass log that would last 100,000 years
  in 90C water.
• For details see Waste Acceptance Product
  Specifications for Vitrified High-level Waste
  Forms http//web.em.doe.gov/waps/

27
RCRA Regulated Wastes

• HLW is a mixed waste, but, from
  http//www.epa.gov/radiation/mixed-waste/mw_pg5.ht
  mvitri
• Vitrification is the process of converting
  materials into a glass-like substance, typically
  through a thermal process. Radionuclides and
  other inorganics are chemically bonded in the
  glass matrix. Consequently vitrified materials
  generally perform very well in leach tests. EPA
  has specified, under the land disposal
  restrictions, vitrification to be the treatment
  technology for high-level waste (55 FR 22627,
  June 1, 1990).

28
What Qualification is used?

• ASTM C1220-92 HLW Glass Leach Test MCC-1
• ASTM C1285 PCT Nuclear Glass Product Control Test
• The objective is to develop a product with a
  leachability index greater than 12
• Recall that the ANSI 16.1 Leach Test went for a
  leachability index greater than 6, and we saw
  that at LI6, a 1cm cube can dissolve in less
  than a year. By extrapolation, at LI12, it
  would last a million years
• PCT is a 7 day, 90C water dissolution test using
  100 to 200 mesh crushed glass. Measure the B,
  Na, and Li leached.

29
HLW Repository WAC, continued

• Table 3  Normalized PCT Leaching Release Rates
  for  Simulated LLW Glass Produced by the
  Westinghouse Plasma Process
•         Sample             Sodium     Silicon    
  Boron     Lithium Test 1    W1G7-106T        
  1.122         0.198         0.173     0.524   
  W1G7-015T         0.296         0.111        
  0.097     0.508    W1G7-017T        
  0.285         0.092         0.093     0.511   
  W1G7-019T         0.198         0.097        
  0.070     0.527    W1G7-021T        
  0.180         0.097         0.063     0.480   
  W1G7-023T         0.192         0.110        
  0.068     0.477 Test 3    W1G7-304T        
  0.553         0.188         0.155     0.203   
  W1G7-310T         0.816         0.235        
  0.236     0.159    W1G7-317T        
  0.650         0.190         0.174     0.124
• SRTC Coupon         0.51           
  0.09           0.52       0.27
• EA Glass                 10.7            
  3.8             13.1         9.4  
• Example from http//www.westinghouse-plasma.com/ll
  w.htm