E-Commerce Decalstruction Site Safety

Transcription

1 GENERAL METHODOLOGY AND PREPARATION OF AN OPERATION TYPE: THE CASE OF BUGEY 1 Gérard LAURENT EDF-CIDEN IRPA CONGRESS

2 Sites being deconstructed

3 Sites being deconstructed

4 Specific features of the deconstruction sites Very dosant sites when reaching equipment close to the core, Little national OF, international OF (notably from the US), A significant portion of the input data are estimated and calculated, Very significant waste problem which does not exist at such a level operationally, need to retain the outlets (notably VLLA),

5 Specific features of the deconstruction sites Evolving configuration of installations along the site, important worker safety area. Significant contamination problems linked to the resuspension of radioactive materials following the use of aggressive cutting methods, in particular in the case of thermal cutting and/or the presence of alphas. Problems of discharge are generally weak (cf. US Feed Back) but an impact approach is necessary, notably vis-à-vis public enquiries. Partial/total release of the sites. What to do with VLLA soil and concrete?

6 Development of dismantling scenarios The choice of reference scenario is made in several stages (combination of ideas, pre-project, detailed pre-project) whilst taking into account all the industry players involved in deconstruction Ultimately leading to: one dismantling authorization decree in support of this, a safety report and support studies A multi-industry team (civil engineering, waste, deconstruction technology, radiation protection, safety, security, environment, etc.) supports the development of the scenario

7 Development of dismantling scenarios ENVIRONMENT: The choice can be oriented according to certain environmental constraints, notably filtration. In general, the constraints are proportional to those of the RP (e.g. thermal cutting of activated structures) but are much weaker. WASTE: The choice of cutting types is important but: Absolute requirement to limit cutting: Less discharge, Fewer doses, Less waste generated, Less road/rail transport, Fewer costs Need to favor wholly monobloc discharges (PWR pressure vessel, SG, etc) Only envisage cutting if this is obligatory.

8 Development basis of dismantling scenarios RP: significant parameter that influnces technology choices RP studies include, among others: a detailed analysis of work conditions at the sites a detailed EDP which adheres to the scenario and enables the admissibility of this in regards to RP to be judged at the end of the cycle.

9 Development of dismantling scenarios The need for a lock-out period between The choice of scenarios and products which are: The EDP for the RP Environmental impact studies, Waste studies If one of these products proves to be unacceptable, the scenarios will need to be locked out

10 The environment product : impact study Linking of two stages: Source term released into the environment, Impact on water, on the air. This last term is similar to the impact analyses developed for the operating units and will not be developed here (same methodology, same tools, same references) In general, for EDF s operating units, the impact is low. In the case of mixed sites, the dismantling unit impact < operational unit impact

11 Source term released into the environment It is a function: Of the planned linking of dismantling operations, Of the radiological inventory: Originating from activation by the neutron flow Originating from contamination Release into the intra muros water and air vectors is calculated by a cascade of release factors that correlate to the choice of cutting types (MDM, AWJ, mechanical, plasma, etc.) Discharges into the environment are a function of the type of filtration in operation and which influence the choice.

12 The RP product development of WSSs/RP Forecasting the linking of dismantling operations Data arising from planning the deconstruction scenarios (number of participants, VTE, complexity of work, etc.) Knowledge of the source term and dose rates (conditions of work) Source term: characterization by sampling, measurement, thanks to the compilation of an installation s history, by simulation (activation calculations with the TRIPOLI, DARWIN and PEPIN codes CEA studies) Calculation iterations measures necessary to take into account impurities generating significant activity when they are not known at the time of supply. Dose rates: ddd and zoning defined based on mapping completed in situ and by simulation thanks to the structures activation data.

13 The RP product development of WSSs/RP Internal contamination and exposure All measures have been taken for the internal exposure to be considered negligible at EDF key factor the associated dose not taken into account in the EDPs Levels of contamination measured on-site, estimated on future sites based on coefficients of resuspension specific to the types of work undertaken.

14 Use of PANTHERE type models Estimate the projected dose rates in the framework of scenario studies with variable installation configurations that no longer correspond to the installation s initial state to guide the technical choices and to define a reference scenario for the development of EDPs Complete a projected zoning of affected areas at the dismantling sites

15 Example of BNI N 45: Bugey-1 Characteristics of Plant 1: BUGEY-1 INCA UNGG reactor: caisson-based primary circuit, annular fuel element Thermal power: 1950 MW Electric power: 545 MWe Fuel: 320t of natural uranium slightly enriched in 235 U Moderator: graphite stacking (2080t) 9m in height and 12.20m in diameter Coolant: gaseous CO 2 under 41.5 bar pressure exchanger entry temperature: 402 C exchanger exit temperature: 217 C

16 Charactristic dimensions: External height External diameter Current thickness of the concrete wall Height of the interior cavity Internal diameter : m : m : 5.50 m : m : m

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18 Dismantling scenario - principles Underwater dismantling of internal equipment Opening of the upper slab Top-down dismantling Biological protection of operators via a wall of water Teleoperation close up Technical flexibility (management of uncertainties) Industrial feasibility (Fort St Vrain Feed Back) Use of thermal tools and several workstations

19 Dismantling scenario - stages 1. Dismantling and refitting of premises outside the caisson 2. Extraction of operational waste 3. Dismantling of the caisson Preliminary operations Opening of the BTS Dismantling of upper internal equipment Cutting of the shaft s activated civil engineering structures Lowering of the platform Dismantling of the plates and support area Total discharge of the caisson Dismantling of lower internal equipment Treatment of the lower part of the shaft 4. Decontamination 5. Remediation of the site

20 RP calculations input data source term Main characteristics of the sources: Already discharged uranium fuel. Most activated areas: stainless steel structures located close to the core Main radioelement: 60 Co from the neutron activation by filiation of the 59 Co and 58 Fe present in the steel structures Only the activated structures are modeled the contamination is not taken into account (distribution is too heterogeneous) Reported sources for the calculations: Complex and detailed spatial distribution of the sources The majority of the source term is based on CEA/SERMA calculations: Mapping of the flows in the reactor with the help of the TRIPOLI.3 code (future TRIPOLI.4) Calculation of the activations with the help of the code system DARWIN/PEPIN.2 Certain sources have been recalculated analytically on the basis of base equations of the neutron activation: dn B = [ Φ. σ A. N A λb. N B ]. dt so as to adjust the impurity rates to the re-estimated values.

21 Radiological state of the caisson in 2010 Calculated values (PANTHERE) in the upper part of the caisson, measured in the lower part 220 msv/h 30 msv/h 60 µ Sv/h 160 µ Sv/h Surfacie Contamination :? : 3020 Bq/cm²? : 0,18 Bq/cm² (Ratio?/? = )

22 Discharge and cutting of the caisson shaft s activated civil engineering structures Reinforced transfer bell (20cm steel) (6cm needed in the phase) 40 µsv/h max to 1m (2010) µsv/h to 1m (2010) High-pressure water jet cutting Work areas for the extraction of the 6 FAMA concrete rings green zc 200 µsv/h (2010) PF 5 successive drops in water level but no platform drop (operations completed from the bridge) 460 msv/h (contact with air) Support area jacks

23 Dismantling scenario Drainage and waste conditioning channel

24 Copyright CEA

25 THE RESULTS: RP Reminder: 1 RGV (Steam Generator changing) : 0.6 hsv Operational collective dose for 1 unit: 0.7 hsv

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27 THE RELEASES: 1/GAZEOUS Activité rejetée à l'atmosphère (Bq/an) Période 1 Période 2 Radionucléides N N+1 N+2 N+3 N+4 N+5 N+6 N+7 N+8 N+9 N+10 N+11 N+12 N+13 N+14 N+15 H E E E E E E E E E E E E E E E+07 C E E E E E E E E E E Co E E E E E E E E E E E E E+01 Fe E E E E E E E E E E E E E E+00 Cl E E E E E E E Ni E E E E E E E E E E E E E E E+01 Ar E E E E E E E E E+08 Eu E E E Eu E E E Ni E E E K E E Ca E E E Sr E E E E E E E E E E+04 Cs E E E E E E E E+03 Sm E E Eu E E Total H3 2.50E E E E E E E E E E E E E E E+07 Total C E E E E E E E E E E Gaz rares 8.29E E E E E E E E E+08 Total β/γ 2.44E E E E E E E E E E E E E E E E+04

28 THE RELEASES:

29 Summary of required maximum releases values radioactive releases Période 1 Radionucléides Rejets radioactifs gazeux Activités annuelles (GBq/an) Rejets radioactifs liquides Activités annuelles (GBq/an) Tritium Carbone 14 / / Autres produits de fission et d activation émetteurs β/γ 0,1 0,1 Synthèse des activités annuelles demandées pour les rejets radioactifs gazeux et liquides pendant la période 1 Période 2 Radionucléides Rejets radioactifs gazeux Activités annuelles (GBq/an) Rejets radioactifs liquides Activités annuelles (GBq/an) Tritium Carbone Autres produits de fission et d activation émetteurs β/γ 0,4 15 Synthèse des activités annuelles demandées pour les rejets radioactifs gazeux et liquides pendant la période 2 Nota : «Année extrême»

30 THE RELEASES : Reminder Unit 900 operation (per year) Regulations Gases Actual Gases Regulations Liquids Actual Liquids Tritium 2 TBq 0.23 TBq 185 TBq 11 TBq C TBq 11 GBq }111 GBq } 2 TBq PA/PF GBq 0.3 GBq

31 Some lines of thought for the future

32 Radiological inventory => Keystone of the dismantling 1. Calculations In particular: The need to work at two levels Long-distance flow of neutrons ( biasing method with cooperation of CEA) Quantification of uncertainties Quantification of radiation source by calculation. Development of REMCO software to quantify the radionucleides transfers on the steel and concrete substrates (partnership with Ecole des Mines and CNRS)

33 Radiological inventory => Keystone of the dismantling 2. Measures for consolidating the calculations: Work closely with the calculator Definition of a range of equipment From the more traditional: Gamma camera Muro video CZT spectroscopy Isocs (soils, GC) Traditional core boring

34 Radiological inventory => Keystone of the dismantling To the more recent: US TRUPRO core boring, (Feed Back from US) Surface measurements in order to replace core boring (CEA, Kourtchatov, EDF/R&D) Tritium measures in the soil via vapor injection (EPRI/USA)

35 Lines of thought for the future 3. Growth of Feed Back US (7 sites, 7 commercial reactors dismantling) Main lessons: Importance of monobloc discharge (Safety, Authority and ANDRA to be trained) Choice of cutting techniques (importance of mechanical choice and choice of AWJ, MDM) Importance of prototype tests (not only tool tests) Water treatment Management of soils and ground waters (4 sites have been or are in the process of being released as green field sites)

36 Comparison of US Plant Statistics

37 Line of thought for the future Management of soils and ground waters: Target is excavation but interest in burial of VLLA concrete if the ownership of the site is retained preservation of ANDRA outlets (ref: MORVILLIERS: 650,000m 3 Mass at 30 years CEA/AREVA/EDF (without increases in density): 840,000m3). If the VLLA structures are left underground (to preserve the VLLA outlets in the framework of sustainable development), if the ownership of the site is retained Very strong interest in working on the exposure factors depending on the future use of the site (cf. US Feed Back).

38 Radionuclide Soil DCGLs using Resident Farmer Scenario (CY - RESRAD) (Bq/g) Soil DCGLs using Industrial Worker Scenario (Rancho Seco - RESRAD) (Bq/g) Increase in DCGL using Realistic Scenario C E E Million Times Co E E Times Ni E E Million Times Sr E E+02 4,200 Times Cs E E Times Cs E E Times

39 Lines of thought for the future 4. Some additional pieces of information Inhalation risk: Importance of optimized approach re exposure/inhalation? Definition of detailled studies of alpha type posts: E.g. at Saint-Laurent, drawing inspiration from what has been done for the operating units with EDF/R&D: Resuspension factors Size of aerosols Solubility

40 Lines of thought for the future Decontamination of concrete: Technical alternatives and alleviation of RP constraints (less trying work) Use of air sensors

41 Lines of thought for the future Even if the sites push us : We need to maintain a strong line: Anticipation about R&D and Engineering