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SEP. 12, 2007

Sung, Ki-Bangkbsung@khnp.co.kr

Reduction Method of Spent Resin Generated from SG BD  Ion Exchangers of PWR NPPS

Reduction Method of Spent Resin Generated from SG BD  Ion Exchangers of PWR NPPS

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1. Introduction

2. Review of the early SGBD IX Replace Criteria

3. Experiment of IX Resin Capacity

4. Review of Experimental Results

5. Conclusions

ContentsContentsContentsContents

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KHNP’s R&D Institute (1)

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KHNP’s R&D Institute (2)

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KHNP’s R&D Institute (3)

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○ Background In Project of Kori #3,4 NPP PSR, Main system of LLW Resin : SG BD Demineralizer

Cause : Secondary Side water pH control agent : NH3 ETA-AVT ⇒ The SGBD cation loads was increased about 2~3 times Spent Resin Radwaste : Large volume and no Industrial waste…

Not easy to treat the ash, though spent resin is almost disposal object itself

PSR Team treated as safety issue item PSR Team(NETEC) and Kori 2 Chemistry Section agreed to the problems a

nd solved the sophisticated problems

1. Introduction (1)

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Block the leaked

ActivitiesRecovery Heat

Recovery BD Bleed

water

Capacity : 5000ℓ×2eaDesign flow : 45ℓ/secNormal flow : 45ℓ/sec

SG BD system’ functions

1. Introduction (2)

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SFP IX2.0ton (9.4%)

LRW System IX1.7ton (7.1%)

CVCS IX3.3ton (18.9%)

SG BD Demin15.4ton/Yr(65%)

Spent IX Resin Source

0 22.4 ton/Yr2.12 t

3.71 t

7.95 t

1. Introduction (3)

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IX Mechanism

Ion Exchange Resin ?

Model of Ix ResinBead of amorphous

and sphere type high polymers

100billions IX sites / bead

1. Introduction (4)

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2. Review of the early SGBD IX Replace Criteria (1)

• IX Resin Replacement Procedures of SGBD IX - No standard Criteria of SGBD IX

- Na was a typical ion to determine the IX removal capacity in many plants. - However, Na was not a typical ion to determine IX removal capacity other plants ( See the next page table )

In USA NPPs, (from EPRI report)

In Domestic Plants,

• IX Resin Replacing Procedures of SGBD IX - 22 of 73 PWR plant didn’t consider the Na ion as IX replacement Criteria

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CriteriaPlnat

IX Replacing Criteria

noteOperation Demin. After Demin.

A Plant Na+ ≥ 5ppbC.C ≥0.5 μS/ ㎝

Na, Cl-, SO4-2 ≥ 2 ppb  

B Plant Na+. DF ≤1 Na+. Cl-, C.C  DF ≤1 DF = Inlet Conc.      Outlet Conc.

C Plant SO4-2 DF ≤1 SO4

-2 DF ≤1  

D Plant C.C increase or Na+≥2ppb C.C≥0.2 μS/ ㎝

Na+, Cl-, SO4-2 ≥ 2ppb  

E PlantC.C≥0.5μS/ ㎝

Na+, Cl-, SO4-2 ≥ 2 ppb NA

1 Operation, 1 Stand-by

F Plant C.C≥0.1μS/ ㎝ NA “

G PlantC.C≥0.1μS/ ㎝

Na+≥3 ppb Cl-, SO4-2≥5ppb NA “

Table : IX Exchanger Replacement Criteria of Domestic Plants

2. Review of the early SGBD IX Replace Criteria (2)

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Scheme and Shots3. Experiment of IX Resin Capacity (1)

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Ion selectivity experiment with H-type IX resin

Volume Flow

NH4 Na CsETA

3. Experiment of IX Resin Capacity (2)

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ETA, NH4, Na Ion selectivity experiment with Cs-type IX resin

Na

Cs

ETA

NH

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3. Experiment of IX Resin Capacity (3)

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ETA

NH4 Na

Cs

NH4

Na

ETA

Cs Saturated IX Resin

Same characteristics of new IX Resin

4. Review of Experimental Results (1)

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• Experiment : 1/80000 of 2.5 ㎥ which was equal to 30 ㎖ of resin capacity and experiment was achieved for resin which is 30 times of addicted chemical material •  Experimental result (ion selectivity on resin) : H+  <  NH4 + ≤  ETA+ <  Na+  < Cs+  

Ionmolecular

weight

ion concentrationsystem

concentration(ppm)

ratio withsystem ion

concentration(ppm)     (meq/l)

ETA+ 61.08 122.16 2 3.5 35

NH3+ 17 34 2 0.2 170

Na+ 23 46 2 0.001 46000

Cs+ 133 266 2 0 ∞

total 101.08 202.16 8 3.701 - 

Ion Absorbing Capacity on Resin

4. Review of Experimental Results (2)

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•  ETA       0.5 [Output conc./Input conc.] Breakthrough time(T) ->      (ETA+NH3) : Na : Cs = 2T : 3T : 4T     This phenomenon came from ETA/NH3, Na and Cs ‘s different selectiveness.

•  NH3         NH3 was eluted after ETA and exchange reaction was faster than ETA.    ※ NH3 was produced from ETA or N2H4 which removes Oxygen. •  Na      Na’s sensitivity was stronger than NH3 or ETA. So, Na was eluted after NH3 or ETA.   High Peak position of Na Conc. was overrode on Cs’s conc. 1.0 meq/ℓ(half input Conc.)   ⇒ Cs extrude Na

•  Cs      Cs has S-shape breakthrough characteristics like single ion and it was absorbed on IX resin. Cs was not affected by other ions, and Its behavior look like single ion solution.

4. Review of Experimental Results (3)

Ion Breakthrough Curve Characteristics

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  - ETA was not impurity in system, and should not be removed at deminerlizer (On the contrary it should be circulated)   - The small Na leakage from new resins was not controlled and excluded at demineralizer exchange criteria.   - Even impurities by outside influx was suddenly increased, the impurities concentration should be decreased in proportion to circulating volume as time passes. Impurities, concentration should be decreased.

    Table. The SG blowdown water quality of PWR

Operation Operation modeNa criteria

(ppb)Cl criteria

(ppb)

Startupoperation

reload→ cold standby (mode 6-5) ≤ 100 ≤ 100

hot shutdown (mode 4) ≤ 100 ≤ 100

hot standby (mode 3) ≤ 100 ≤ 100

startup operation (mode 2) ≤ 100 ≤ 100

Reactor power

operation

reactor power (5~30%) ≤ 100 ≤ 100

reactor power ( 30%) ≤ 20 ≤ 20

4. Review of Experimental Results (4)

The resin replacement criteria of cation resin

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• Na concentration should be less than 100ppb at maximum or stop operation. If the limited concentration at the second step is less than Na 100ppb, the concentration at Na DF 10 should be 10ppb.• DF 10 of Na Spec value (20ppb) is 2ppb, and Max conc. of Na is 3ppb at operation over 30% generation. Therefore sum of them is less than 5ppb.    • The water quality level is less than Na concentration(5ppb). Therefore, improvement of cation resin change criteria is that the Na outlet conc. is reasonable to be selected less than 5ppb.• Cl , SO4

-2 and Conductivity would be derived from system parameters as below.

◆ The resin exchange criteria of SG blowdown demineralizer

-  exchange criteria of mixed bed : [Na, Cl ≥ 5 ppb ] 

-  reference exchange criteria : [SO4-2 ≥ 5 ppb,  C.C ≥ 0.3 ㎲ / ㎝ ]

4. Review of Experimental Results (5)

The resin replacement criteria of IX resin

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Table : Ion load for water quality of flow water

ItemIon

Max.conc (ppb) M.W (g./mol)

Ion load( x 10-9 eq/ℓ)

Considered ETA, NH4 not considered ETA, NH4

ETA 5,000 61.08 81.86 NA

NH4+ 500 17.00 29.41 NA

N2H4 50 32.00 1.56 1.56

Na+ 20 23.00 0.87 0.87

total 115.05 3.78

Anion Max organic acid x 1 Max organic acid x 5

Cl- 20 35.50 0.56 0.56

SO4-2 20 96.06 0.42 0.42

SiO2- 100 60.08 1.66 1.66

Acetic acid 20 60.05 0.333 1.67

Glycolic acid 20 76.05 0.263 1.31

Formic acid 20 46.02 0.435 2.17

total 3.67 7.80

4. Review of Experimental Results (6)

The SGBD Ion Exchanger’s cation/anion mixing ratio

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Table.  Calculated Resin Volume with system ion loads

ItemResin

Ion Load of System(x10-9 eq/ℓ) Removal Cap

acity of Resin *(eq /ℓ resin)

Calculated Resin Volume capacity

(x 10-9 ℓ resin)

ETA considering

ETA not considering

ETA considering

ETA not considering

Cation 115 3.78 1.8 63.9 6.5

Anion

Max organic acid x 1

3.67 3.67 1.2 3.1 3.1

Max organic acid x 5

7.80 7.80 1.2 2.1 2.1 ◆ SG BD demineralizer’s cation/anion resin mixing ratio

  - the ratio of cation and anion resin was 10 : 1 considered ETA load    - the ratio of cation and anion  resin was 1 : 3 excluded ETA load   - The Mixing ratio of Resin (margin : ETA elution effects) 3 : 1

4. Review of Experimental Results (7)

The SGBD Ion Exchanger’s cation/anion mixing ratio

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Satisfaction of PWR FSAR’s Requirements

Saturated IX with ETA Capture the Na and Cs ion

Cs+ > Na+ >  ETA+ ≥ NH4+ > H+

Confirm the cation IX Resin Selectivity in ETA solution

No load IX Resin for ETA or NH4

Verify the Cs ion Selectivity of H-, ETA-saturated IX

Satisfaction of EPRI secondary water Guidelines

Confirm the Na ion Selectivity in ETA solution

5. Conclusions (1)

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Establish Spent Resin change Criteria

1Standardization Spent Resin Criteria and Mixing IX Resin

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Examined Na’s behavior in system

4Obtain ion Selectivity for H-type ion

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Technical Effects

5. Conclusions (2)

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Max. removal Capacity of Resin

Reduce works on Radiation area

Reduce Spent IX resin(370t/yr)

Save the Cost(3.3billionWon/total

Solving Problem example with another team

Other Effects

Min. Low Level Radioactive Wastes

Min. Radiation Exposure

Water quality treatment tech.

Co-works

5. Conclusions (3)

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Thank you for your attentions !