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NS&E 618 September 26, 2003 Objectives Review of Waste Classification Identification, and Treatment of Gaseous Radioactive Wastes Fission On the homework Still worrying about radiation-Ci calculation

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ns e 618
NS&E 618

September 26, 2003

Objectives

Review of Waste Classification

Identification, and

Treatment of Gaseous Radioactive Wastes

GAB - NSNE 618

fission
Fission

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on the homework
On the homework
  • Still worrying about radiation-Ci calculation
  • Suppose you have a line (cylinder) source and place a survey meter on the outer diameter

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websites
Websites
  • http://www.westrain.org/WReactor/ThermodynamicsCh3.PDF steam jet
  • http://www.nucleartourist.com/ views of a nuclear reactor
  • http://www.eas.asu.edu/~holbert/eee460/nucleartopics.html#EEE460-Waste excellent waste links
  • http://www.philrutherford.com/radiation_software.html radiation computation software I recommend that you download and install “radiation decay”

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waste classification
Waste Classification

Not radioactive

Air

Water

Soils

Solids - No BRC

10 CFR 20 App. B

NRC and EPA allow Perf. Based Definition

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waste classification based on radioactivity
Waste Classification Based on Radioactivity

Spent Fuel, HLW (First Cycle Raffinate)

10 CFR 60; and 10 CFR 63

LLW

A

B

C

GTCC

TRU -- A DOE Category only -- If there were significant commercial quantities there might be commercial TRU, but there isn’t

10 CFR 61

10 CFR 61

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nrc waste categories
NRC Waste Categories
  • Class A
  • Low levels of radiation and heat, no shielding required to protect workers or public, rule of thumb states that it should decay to acceptable levels within 100y.
  • Class B
  • Has higher concentrations of radioactivity than Class A and requires greater isolation and packaging (and shielding for operations) than Class A waste.
  • Class C
  • Requires isolation from the biosphere for 500 years. Must be buried at least 5 m below the surface and must have an engineered barrier (container and grouting).
  • Greater Than Class C
  • This is the LLW that does not qualify for near-surface burial. This includes commercial transuranics (TRUs) that have half-lives>5y and activity>100nCi/g.

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10 cfr 61 table 1
10 CFR 61 Table 1

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table 1 rules
Table 1 Rules
  • If the concentration does not exceed 0.1 times the value in Table 1, the waste is Class A.
  • If the concentration exceeds 0.1 times the value in Table 1 but does not exceed the value in Table 1, the waste is Class C.
  • If the concentration exceeds the value in Table 1, the waste is not generally acceptable for near-surface disposal.
  • For wastes containing mixtures of radionuclides listed in Table 1, the total concentration shall be determined by the sum of fractions

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10 cfr 61 table 2
10 CFR 61 Table 2

There are no limits established for these radionuclides in Class B or C wastes. Practical considerations such as the effects of external radiation and internal heat generation on transportation, handling, and disposal will limit the concentrations for these wastes. These wastes shall be Class B unless the concentrations of other nuclides in Table 2 determine the waste to the Class C independent of these nuclides.

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table 2 rules
Table 2 Rules
  • If the concentration does not exceed the value in Column 1, the waste is Class A.
  • If the concentration exceeds the value in Column 1, but does not exceed the value in Column 2, the waste is Class B.
  • If the concentration exceeds the value in Column 2, but does not exceed the value in Column 3, the waste is Class C.
  • If the concentration exceeds the value in Column 3, the waste is not generally acceptable for near-surface disposal.
  • For wastes containing mixtures of the nuclides listed in Table 2, the total concentration shall be determined by the sum of fractions rule

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rules for table 1 2 wastes
Rules for Table 1&2 Wastes
  • If radioactive waste contains a mixture of radionuclides, some of which are listed in Table 1, and some of which are listed in Table 2, classification shall be determined as follows:
  • If the concentration of a nuclide listed in Table 1 does not exceed 0.1 times the value listed in Table 1, the class shall be that determined by the concentration of nuclides listed in Table 2.
  • If the concentration of a nuclide listed in Table 1 exceeds 0.1 times the value listed in Table 1 but does not exceed the value in Table 1, the waste shall be Class C, provided the concentration of nuclides listed in Table 2 does not exceed the value shown in Column 3 of Table 2.
  • Classification of wastes with radionuclides other than those listed in Tables 1 and 2. If radioactive waste does not contain any nuclides listed in either Table 1 or 2, it is Class A.

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waste classification application what are these
Waste Classification Application - What are These?

Off Spec Fuel Elements

Sludge from Neutralized HLW Tanks (SR, HANF, WVDP)

Supernate from Neutralized HLW Tanks

Pump withdrawn from a Neutralized HLW Tank

4000 Ci Medical Cobalt source (1 in diam x 4 in long)

INEEL Sodium Bearing Waste

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waste classification application cont
Waste Classification Application, cont.

Failed Am-241 smoke detector source (2 Ci in a dime-sized capsule)

500 Ci H-3 source

Reactor metal in a 55 gal drum with 50 mCi Nb-94

Drum (55 gal) containing Cs-137 reading 100 mR/hr at surface

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waste classification application cont15
Waste Classification Application, cont.

1 acre pond, 4 ft deep with 10 mCi Cs-137

Waste from RFP

Graphite from production reactors

Cs-137 capsule from Hanford 35 kCi

Pressurized tank containing 1000 Ci Kr-85

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origins of gaseous species
Origins of Gaseous Species

Activation

C-14 (as CO or CO2

N-16

Ar-41

Fission

Kr-x

Xe-x

Other - H-3 - Radon

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topics
Topics

Source of gaseous releases, 0.12 % failure of fuel cladding

Removal and decay of noble gases

Radiolytic hydrogen and oxygen for BWR and nitrogen recycle in PWR

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major gaseous wastes of concern
Major Gaseous Wastes of Concern

H2 and O2, radiolytically generated, non-radioactive

Kr-85 - Reactor release, fuel reprocessing

N-16 - short term reactor area

H-3 -long term cumulative conversion to and mixing with groundwater

C-14 conversion to hydrocarbons or carbonates and disposed of as solid LLW

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radioactive waste gases
Radioactive Waste Gases

Fission Products – H-3, Kr, Xe, I2

Activation Products – C-14, N-16, A-41

PWR and BWR have different situations

Objective is to keep reactor releases to less than 1 Ci/y or be safe

BWR continuously cycles coolant out of the pressure vessel

PWR retains coolant for up to 6 months

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slide20
PWR

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slide21
BWR

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slide22
SJAE

Note benefits of a SJAE: Motive force is steam

No moving parts

Upon cooling, the steam is just water

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recombination of h 2 and o 2
Recombination of H2 and O2

BWR generates about 150 scfm of H2 and 75 scfm of O2 . (Decomposition of H2O gives 2 moles of H2 for each mole of O2

There is also about 75 scfm air in leakage, and 40 scfm of water vapor

Note that the Kr and Xe are trivial amounts compared to this and the tritium is in the water

Since the steam is condensed to water after passing through the turbine, if this gas is not removed, it will lock the turbine or lead to an explosion or both.

Once removed it is explosive, and must be kept below 4% H2

Therefore, there is a requirement for an effective catalytic recombiner 2H2 +O2 => H2O operating at less than 500 C

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calculations on kr 85 generation
Calculations on Kr-85 Generation

Estimate Kr-85 production from thermal power only

Discuss issues to be considered (on separate file -- “Krypton Released from a Reactor”)

Note that this approach is applicable to all other fission products

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treatment of noble fission product gases
Treatment of Noble Fission Product Gases

PWR and BWR are different

PWR retains gases in primary coolant and most decay occurs there

BWR continually removes gases shortly after they are produced, they must be decayed in order to allow safe release.

See xls. spread sheet computations

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topics of special note
Topics of Special Note

Basis for small particulate filter needs

Hydrogen recombination

Special note on Steam Jet Ejector

Tritium

Combines with oxygen to form Tritiated Water

Can be separated via distillation, electrolysis, catalytic exchange

Extremely expensive when you consider the levels to be separated

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high curie releases
High Curie Releases
  • The 270 – 300 Ci of Kr release greatly exceeds the normal standard of <1 Ci/y, that is why we have a “license to release”
  • Recall, 99.9% of the Kr-85 is still in the fuel. The THORP reprocessing plant in England fought long and hard to operate because at 300 tons per year, it would release about 3*1000*300 Ci/y of Kr-85
  • Tritium annual releases are a about 400 Ci
  • Review 10 CFR 20 Appendix B
    • Foot note 1 for H-3 1E-7 microCi/ml in “semi-infinite cloud”
    • Similar with Kr-85 7E-7 microCi/ml and Xe

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summary of treatment of radioactive gases
Summary of Treatment of Radioactive Gases

Capture and decay Xe and Kr

Kr will become a problem for major fuel reprocessing

Tritium remains a background annoyance

Release and distribute the rest

Major waste gas problem is radiolytic non-radioactive hydrogen and oxygen

Radon - learn to cope with it.

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