Development of a xenon mitigation prototype

Transcription

1 Development of a xenon mitigation prototype Christophe Gueibe, Jos Rutten, Johan Camps, Klaas van der Meer Belgian Nuclear Research Centre (), Mol, Belgium Matthias Auer, Abdelhakim Gheddou, Martin Kalinowski Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), Vienna, Austria Dominique Moyaux, Benoît Deconninck Institute for Radioelements (IRE), Fleurus, Belgium Project financed under the EU JA-V program 1

2 l Objective of the International Monitoring System (IMS): Introduction At least 90% detection capability within 14 days after a nuclear explosion in the atmosphere, underwater or underground for a 1 kton nuclear explosion. l Radioxenons are a key component of the verification of the CTBT l Detection capability international noble gas network (Xe) depends on: l Number and distribution of stations (30 operational actually, 40 are planned) l Minimum Detectable Concentration (< 1mBq/m 3 for Xe-133) l Background level at individual stations of radioxenons from other sources Source Radioxenon release Hospitals Bq/year Be and mainly Xe-131m Nuclear Power Plants ~10 15 Bq/year > 150 sites (> 1000 MW) Radiopharmaceutical facilities ~ Bq/year All RPFs 1 kton nuclear explosion ~10 16 Bq/event Xe-133 if all released 2

3 Project summary l Aim: Develop and test a mobile pilot system for the reduction of xenon emissions (based on physical adsorption) at IRE, Fleurus l Project subdivided in three phases l Phase I: Selection and study of xenon adsorption materials with emphasis on new types of Silver Zeolites l Phase II: Study of operational conditions of a xenon trap and trap design l Phase III: Construction and testing of a mobile trap at the IRE facility l At this stage of the project l Phase I è Finished Main results and corresponding l Phase II è Finished design in this presentation l Phase III è In progress 3

4 Experimental set-up at For tests with stable Xenon Two interchangeable columns that can be - filled with different adsorbent materials - cooled (ice, dry ice, ) - heated (regeneration studies) 4 Thermal conductivity detector (TCD)

5 Xenon adsorption materials l The most promising activated carbon is Nusorb GXK l The most promising silver zeolite is Ag-ETS-10 Ag-ETS-10 highly concentrates xenon in its volume F (cm³/min) T ( C) P (bar) [Xe] (ppm) S. M. Kuznicki et al., Xenon adsorption on Modified ETS-10, J. Phys. Chem. C, 111 (2007)

6 Comparison required adsorbent volume l Hypotheses l Trap used in the venting system of the dissolver l The trap should operate 80 days before regeneration (decay) l 80 days decay è 15 T 1/2 Xe-133 (reduction factor 10 4 ) l No diffusion of xenon atoms in between dissolution! l Adsorbent volume Adsorbent Volume (cm³) RKJ Nusorb GXK 5170 Ag-Chabazite (10-15%) 1100 Ag-Chabazite (25-30%) 600 ~25 Ag-ETS Ag-ETS-10 (T= 60 C) 380 6

7 Ag-ETS-10 Possible issues l Ag-ETS-10 highly concentrates xenon l Radioxenon with high activities in operational conditions at IRE! l Degradation of materials due to the irradiation? l No degradation after a 1 MGy irradiation l Temperature rise in the adsorption column? l Decreasing adsorption capacity and increasing diffusion l Calculation of the temperature inside the column (T > 200 C) l Possible solutions l Mixture Ag-ETS-10 with activated carbon to increase volume l Ag-Chabazite to increase volume of trap l Replacing 1 column by 2 or 4 smaller column (V tot =Cst) l Oversize the adsorption column for equilibrium è T l AND decrease activity by adapting the working process 7

8 l Helium regeneration at different temperatures l 3 hours at fixed temperature Helium regeneration conditions Run C Run C Run C In these conditions, optimized T is C 8

9 Design studies l Different options investigated to l Reduce the activity l Chosen option l Reduce operating time of column (20 d) l More columns l BUT less activity l Oversize columns l Equilibrium 9

10 Working process 10

11 l 2 boxes available for the system l Dimension of one box is too small for 6 columns l One column 100 mm l Pb shielding Dimension constraints Box Door Depth (mm) 650 / Width (mm) Height (mm) è 2 independent systems l 3 columns each l Pb shielding l Gas handling system 11

12 Overview of the system l Limited size l Mobility (on wheels) l Lead shielding l Easily removed l Adsorption columns l Easily removed 680 mm 12

13 Adsorption columns l 3 Identical columns l Volume of each column = 500 cm³ l Optimized L/D ratio = 10 from phase II l L = 400 mm l D = 40 mm l Valves to isolate and remove l Holder to fix in the system l Insertion tube for temperature sensor l Desorption l Adsorption (decay heat) l Filters up and downstream l Filling of adsorption columns l Mechanical vibration 13

14 Gas handling system l Overview l Use of 1 column l Mode in series l 2 columns l 3 columns è Flexibility 14

15 l Adsorbent materials study l Best adsorbent is Ag-ETS-10 (new sample) l Good durability against successive regenerations l BUT highly concentrates xenon è Temperature! l Study of the trap design l Optimized trap geometry è L/D 10 l Optimization of the regeneration conditions Conclusion & Future work l Helium as desorption gas è Optimal T= C for 3 hours l Design of the prototype l Dimension constraints è Small and flexible system l Prototype will be tested l At for initial tests l At IRE for further tests in operational conditions (radioxenon) 15

16 Thank you for your attention! Questions? 16

17 - SCK CEN PLEASE NOTE! This presentation contains data, information and formats for dedicated use ONLY and may not be copied, distributed or cited without the explicit permission of the. If this has been obtained, please reference it as a personal communication. By courtesy of. Studiecentrum voor Kernenergie Centre d'etude de l'energie Nucléaire Belgian Nuclear Research Centre Stichting van Openbaar Nut Fondation d'utilité Publique Foundation of Public Utility Registered Office: Avenue Herrmann-Debrouxlaan 40 BE-1160 BRUSSELS Operational Office: Boeretang 200 BE-2400 MOL 17