PBMR Product Overview Source Term Modelling by xyd32971

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									                 PBMR:
Product Overview & Source Term Modelling

          PSI HTR Dust Issues Meeting
            26 – 27 November 2009

   Paul Scherrer Institut, Villigen, Switzerland
                PBMR:
Product Overview & Source Term Modeling
                      Prepared By:
                        Pieter Goede
                     Marissa van der Walt
                        Lize Stassen
                      Frederik Reitsma


                      Presented By:
    Munyaradzi Makumbe – Project Engineer: Analysis Testing




                                                              2
PBMR PRODUCT OVERVIEW
                              400 MWt Reactor Unit
                              Electricity Generation
      Reserve
     Shutdown
      System
       (small     Fuelling
      o
     absorber      Pipes
      spheres


Reactivity
 Control
 System
 (control
  rods)         Annular Core



                   Side
                 Reflector




                  Cold Gas
                    Inlet

                    Hot Gas
                     Inlet




  De-fuel
  Chutes
   (x3)




                                                       4
        Product change from PBMR 400MWt to 200MWt

o The global financial crisis
     Affected funding of some South African State-owned Enterprises
        • Eskom - Nuclear I (PWR program) delayed.
o Near-term Market Opportunities
     Based on prospective customer requirements – There is an opportunity to service both
      the electricity and process heat markets.
     Decision made to develop a standard nuclear heat supply source capable of servicing
      both markets.
o Modification of the design to service prospects such as:
     The Next Generation Nuclear Plant (NGNP) project in the US
     Oil sands producers in Canada (to extract bitumen from oil sands),
     The petro-chemical industry and large process steam users
o Modular design of ~200MWt (simplified design to reduce risks)
     Modular concept with the potential to link more than one reactor to a single power
      turbine or to supply process steam
     Increase availability with multi-pack – no interruptions of steam supplied to the client




                                                                                        5
                                                          PBMR Products

PBMR   Blower   SG   Pump   Pump      Pump




                            Water /                      Condenser
       Helium
                            Steam




                                             Generator



                                                                Process Heat

         Electricity                                                           Co-generation




                                                                     Fuel


                                                                                           6
                    Where is PBMR now?

   Employees ~ 900 (Centurion & Pelindaba)
   New 200 MWt DPP Rankine Cycle selected (to demonstrate co-generation)
   Design & licensing work underway
   Eskom – host & operator at Koeberg
   Consortium of customers being pursued (petro-chemistry industry and
    large energy users)
   Fuel testing & qualification in Fuel Development Labs at Pelindaba
   Supply chain – localization focus
   Test facilities at Pelindaba & North-West University
   US DOE NGNP participation




                                                                         7
Source Term Analysis & Dust Modelling




                                        8
   Helium Pressure Boundary (HPB) Source Term Calculations


                       Source Terms for:
• Design analysis
                                              Surfaces
• Safety analysis         Breaks
                                             Dust deposition

                                             Atomic plate-out
      Coolant           Maintenance

     Dust activity                           Components
                          Other:
     Atomic activity                             Filters
                          leakage,
                          permeation




                                                                9
                      HPB Source Term Drivers



 Fuel Radionuclide release rates
   Fuel inventory
   Graphite impurities
   Quality of kernel coatings
   Fuel temperatures

 Activation of circulating nuclides
  in coolant and with dust
   Atomic migration phenomena
   Graphite and Metal dust production
   Dust migration phenomena:
     • In coolant
     • With fuel spheres




                                                10
                   PBMR HPB Source Term
                    Modelling History (1)

o SPATRA (FZJ): Initial plate-out evaluations (~2000)
    limitations
       • no precursor sources modelled
       • no dust modelling
o RADAX (HRB): Fission Product (FP) and dust distribution and
  transport (up to 2007/8)
      limitations
         • limited dust modeling (deposition, resuspension, migration)
         • no FP/dust interaction - manual post-processing
         • unrealistic distribution (no dust retained in core, Spent Fuel Tank)
      uncertainties in model parameters
      assumptions difficult to justify without experimental work




                                                                         11
                   PBMR HPB Source Term
                     Modeling History (2)
o Conclusions from Oct 2008 evaluations:
    metallic dust migration and activation models insufficient
    justification for assumed sorption of FP on dust insufficient
o Recommendation: base Source Term analyses on existing
  reactor operating experience
    improved analysis code required
o SPECTRA
    NRG-developed thermal-hydraulic code with FP Transport package
    fully integrated system analysis code for various reactor types
o RADAX/SPECTRA approach requires specific validation data
    challenge to obtain suitable data for all models/phenomena
o Alternative modeling approach adopted – Dust & Activity
  Migration & Distribution (DAMD) development



                                                                     12
                                 Radionuclide Transport Modelling Approaches

                                Bottom-to-Top Modelling                         Top-to-Bottom Modelling

                                 E.g. RADAX, Spectra                                    E.g. DAMD




                                                                                                                                  Integrated Effects Phenomena
  Separate Effects Phenomena




                                                                               Integrated effects phenomena
                                Integration / Combining of                      and correlations derived from
                               separate effects correlations
                                                                                   measurements on an
                                                                               integrated plant, e.g. the AVR
                               Separate effects phenomena
                               and correlations derived from                       Only most dominant
                                  separate effects tests                       phenomena defined explicitly




                                     Scale Separate Effects Phenomena vs. Integrated Effects Phenomena
Reasonable modelling of a full HTR plant depends                          Reasonable modelling of a full HTR plant depends
on:                                                                       on:
• Suitability of the separate effects test conditions                     • Using the AVR to calibrate the migration
• Correct implementation of integration cross-terms                       parameters
• Inclusion of changing separate effects input data                       • Scalability of the dominant phenomena in the
(e.g. surface roughness that changes over operating                       AVR to the HTR plant
life)

                                                                                                                             13
                            DAMD Modelling Approach

                         Dust and Atomic particle Migration Model
                                            DAMD



   Deposition Rates                   Calibrated against AVR           Lift off Rates


Explicit modelling of Forces                                   Explicit modelling of Forces
- Hydraulic force (flow conditions)                            - Hydraulic force (flow conditions)
- Gravity force                                                - Transient forces
                                                               - Centrifugal force
Lumped (non-explicit) modelling
of Forces (e.g. thermophoresis,                                Lumped (non-explicit) modelling
van der Waals Forces)                                          of Forces (e.g. vibrations, van
- Calibrated correlation                                       der Waals Forces)
                                                               - Calibrated correlation




                                                                                           14
   DAMD Results for AVR and PBMR

Note: Only a few results are shown. Many more
    results and experiments are available




                                                15
DAMD AVR Model




                 16
                  Experimental Loops on the AVR

o Vampyr I: 49 exp.’s,
  ’72 –’89
o Vampyr II: 4 exp.’s,
  ’87 – ’88
o Cold Gas Filter: 52
  exp.’s, ’72 –’89
o Dust experiment: S1-
  S15 (both lines), ’84 –
  ’87;
  SA1-SA5 (Line 2),
  ’87–’88
o Dust remobilization
  exp.’s T1 –T5:
  measured in cold gas
  filter, Vampyr I & Dust
  Exp.,
  ’86 – ’88



                                                  17
             AVR Activity Results with DAMD
                     3-Flow Channel Model
o Fuel Temp’s for 20% core by-pass flow
o Fuel performance based on Fuel Release Factors for AVR fuel history



                                                                           DAMD AVR activity 
                                                        1.0E+14                                                                  1000



                                                        1.0E+13
                                                                                                                                 800




                                        Activity (Bq)
                                                        1.0E+12




                                                                                                                                       ROT (°C)
                                                                                                                                 600

                                                        1.0E+11


                                                                                                                                 400
                                                        1.0E+10



                                                        1.0E+09                                                                  200
                                                             Jan‐68    Jan‐72     Jan‐76           Jan‐80     Jan‐84    Jan‐88
                                                                                            Date
                                                                      Ag110m    Cs134      Cs137       Co60   ROT


                                                             3 Flow Channel
                                                             (15% Hot, 70% Average, 15% Cold)

                                                                                                                       18
         DAMD AVR Comparisons: Dust & Activity Values

   Location /      Year       Parameter        Unit    Nuclide     AVR      DAMD        DAMD /
  Experiment                                                     Measured              Measured

All Experimental   Life-   Circulating Dust    µg/m3      -        7.80      8.00           1.0
     Loops         time     Concentration
VAMPYR II Test     1988    Circulating Metal    %         -
   3&4                      Dust Content                            27        19            1.4↓
                                                        60Co     2.5x106    2.4x106         1.0
                   Life-                               110mAg
  VAMPYR I         time      Dust Activity     Bq /g             4.3x106    6.1x106         1.4↑
                                                        137Cs    2.0x107    1.2x108         5.9↑
                                                        60Co     8.9x105    1.2x106         1.4↑
                   Life-                               110mAg
Cold Gas Filter    time      Dust Activity     Bq /g             2.7x106    8.7x106         3.2↑
                                                        137Cs    1.7x107    5.3x107         3.2↑
                                                        60Co     2.4x107    1.6x108         6.4↑
   Blower                                      Bq/m2   110mAg
 Maintenance       1978    Surface Activity                      1.8x108    2.6x108         1.5↑
                                                        137Cs    2.8x109    1.4x1010        5.0↑
                                                        60Co     3.4x105    9.3x104         3.7↓
   DEACO I         2007    Surface Activity    Bq/m2
                                                        137Cs    5.9x107    4.3x108         7.3↑



                                                                                       19
                                                      DAMD AVR VAMPYR Plate-Out Comparisons



                                                      Cs137                                                                                                Ag110m 
                                                                                                                                   1.0E+05
                                  1.0E+03




                                                                                                 Activity Concentration (Bq/cm2)
Activity Concentration (Bq/cm2)




                                                                                                                                   1.0E+04

                                  1.0E+02

                                                                                      Measured                                     1.0E+03
                                                                                                                                                                                                        Measured
                                                                                      DAMD
                                                                                                                                                                                                        DAMD


                                  1.0E+01
                                                                                                                                   1.0E+02



                                                                                                                                   1.0E+01
                                  1.0E+00
                                                                                                                                             0.0   0.5   1.0     1.5    2.0      2.5   3.0        3.5
                                        0.00   0.50    1.00     1.50    2.00   2.50
                                                      Tube length (m)                                                                                          Tube length (m)


            Comparison between VAMPYR I V09 test                                                                                   Comparison between VAMPYR II V01 test and
            and DAMD for Cs137 Plate-out on 15Mo3                                                                                  DAMD for Ag110m Plate-out on Incoloy 800
                            tube                                                                                                   tube


                                                                                                                                                                                             20
                                                          DAMD AVR % Plate-Out
                         % Plate‐out in AVR primary circuit at mid‐ and end‐of‐life 
                          Core Ceiling Structure        Steam Generator                      Annular Return Flow Channel
              100

               90
                                                                                                                                  8
                                                                                                                                                              % Plate-out in AVR primary
                                                                                                                                  7
               80                                                                                                                                             circuit low due to surfaces




                                                                                                                                      Dust layer thickness 
                                                                                                                                  6
               70
                                                                                                                                                              covered with dust, except in
% plate‐out




                                                                                                                                  5
               60

                                                                                                                                                              high flow areas with




                                                                                                                                              (µm)
               50                                                                                                                 4

               40

               30
                                                                                                                                  3                           reduced dust coverage
                                                                                                                                  2
               20
                                                                                                                                  1
               10

                0                                                                                                                 0
                    10                             20                            30                                          40
                                                        Component nodes
                                    Cs137 % p/o_'78          Ag110m % p/o_'78                             Cs137 % p/o_'89
                                    Ag110m % p/o_'89         Dust layer thickness_'78                     Dust layer thickness_'89

                                                                                             % Plate‐out in AVR Vampyr I at mid‐ and end‐of‐life 
         % Plate-out in Vampyr I                                                            100                                                                                                8

         experiment high due to                                                              90
                                                                                                                                                                                               7




                                                                                                                                                                                                   Dust layer thickness (µm)
                                                                                             80
         insertion of clean tube at start                                                    70
                                                                                                                                                                                               6
                                                                              % plate‐out




         of experiment; graphs are a                                                         60
                                                                                                                                                                                               5


         function of temperature                                                             50

                                                                                             40
                                                                                                                                                                                               4

                                                                                                                                                                                               3
         effects governing dust – F.P.                                                       30
                                                                                                                                                                                               2
         interaction                                                                         20
                                                                                                                                                                                               1
                                                                                             10

                                                                                              0                                                                                                0
                                                                                                  1

                                                                                                                                               Component nodes
                                                                                                      Cs137 % p/o_'78                          Ag110m % p/o_'78           Cs137 % p/o_'89
                                                                                                      Ag110m % p/o_'89                         Dust layer thickness_'78                   21
                                                                                                                                                                          Dust layer thickness_'89
     DAMD distribution of graphite & metallic dust, Co60,
            Cs137 and Ag110m activity in AVR

                             Dust and activity distribution in AVR at EOL 
                 60
% of AVR total




                 50

                 40

                 30

                 20

                 10

                 0
                      Core   CCS    SG       ARFC    Blower Blower    FHS   SFT   Vampyr   CGF   Dust Vampyr   HPS    Core    SG
                                                        1      2                    1            Exp    2            Bypass Bypass
                                                                    Components 

                             Graphite Dust          Metallic Dust     Co60 activity    Cs 137 activity    Ag110m activity




                                                                                                                            22
DAMD as PBMR Design Tool
Example: 60Co Dust Activity
Distribution




                      23
                 Data Requirements Stemming From
                        DAMD Development
o Integrated effects data:
     A code that models full plant migration of dust, fission and activation
      products must take integrated effects in the whole plant, including the
      core and fuel handling system, into account to model accurately. Dust
      deposition/lift-off and fission product plate-out cannot be considered
      separately.
o Separate-effects data:
     Separate-effects dust deposition tests in simple configurations like pipes
      are required for evaluating deposition models in selected areas of
      integrated plant models.
o Dust migration through attachment to fuel spheres:
     This is a driving force for the distribution of dust, fission and activation
      products in a pebble-bed plant.
     Experiments for testing the migration of dust on fuel spheres would be
      useful for validation of an integrated code like DAMD.



                                                                                 24
    PBMR Code Verification and Validation (V&V)

o FP and dust transport Code V&V requires specific data
    data must be relevant to phenomena and conditions modelled
    depends on modelling approach
o SPECTRA (bottom-to-top) approach requires:
    data from separate effects, combined effects, and fully integrated
     effects experiments
o DAMD (top-to-bottom) approach requires:
    specific inputs, eg.
       • dust generation data, dust classification (metallic and graphite)
       • dust mass retention in core and fuel handling system
    identification of important phenomena to be modelled explicitly, vs
     as lumped parameters
    data from separate and combined effects experiments




                                                                          25
          Potential Value of PSI facility for PBMR


o Data of interest:
       graphite and metallic dust classification or morphology
       core dust generation mechanisms
       validated core dust generation models
       dust migration data (in-core and balance of system)
       operational effects of dust (clogging, heat transfer efficiency)
       ranked phenomena regarding dust generation and transport
       deposition and resuspension validation data and models
       data from both separate effects and integrated effects experiments




                                                                         26
THANK YOU.




             27

								
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