Status Report on the NFS project (September 2013)

Transcription

1 Status Report on the NFS project (September 2013) TITLE of the Project: Neutrons For Science (NFS) Spokespersons (maximum 3) with one corresponding spokesperson: Xavier Ledoux, CEA/DIF F Arpajon, present address GANIL, Stanislav Simakov, FZK, Karlsruhe Members of the Collaboration: X. Ledoux, E. Bauge, G. Belier, T. Caillaud, A. Chatillon, T. Granier, O. Landoas, B. Rossé, J. Taïeb, I. Thfoin, C. Varignon, CEA/DIF, Arpajon, France D. Doré, F. Gunsing, T. Materna, S. Panebianco, D. Ridikas (on temporal leave to the IAEA, Vienna), CEA/DSM/Irfu/SPhN, Saclay, France M. Aïche, G. Barreau, S. Czajkowski, B. Jurado, CENBG, Gradignan, France G. Ban, F. R. Lecolley, J. F. Lecolley, J. L. Lecouey, N. Marie, J. C. Steckmeyer, LPC, Caen, France P. Dessagne, M. Kerveno, G. Rudolf, IPHC, Strasbourg, France P. Bem, M. Majerle, J. Mrazek, J. Novak, E. Simeckova, NPI, Řež, Czech Republic C. Gustavsson, S. Pomp, Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden U. Fischer, A. Klix, S. P. Simakov (on temporal leave to the IAEA, Vienna), KIT, Karlsruhe, Germany J. Grinyer, B. Jacquot, F. Farget, J. P. Wieleczko, GANIL, Caen, France M. Avrigeanu, V. Avrigeanu, C. Borcea, F. Negoita, M. Petrascu, NIPNE, Bucharest, Romania S. Oberstedt, A.J.M. Plompen, JRC/IRMM, Geel, Belgium M. Fallot, L. Giot, Subatech, Nantes, France A. G. Smith, I. Tsekhanovich, Department of Physics and Astronomy, University of Manchester, Manchester, UK O. Serot, CEA/DEN, Cadarache, France L. Perrot, L. Tassan-Got, IPNO, Orsay, France E. Balanzat, B. Ban-d état, S.Bouffard, S. Guillous, J. M. Ramillon, CIMAP, Caen, France A. Oberstedt, Örebro University, Örebro, Sweden J.C. Sublet, CCFE, United Kingdom 1 Introduction The Neutrons For Science (NFS) facility is a component of LINAG Experimental Area of SPIRAL-2. NFS will be composed of a pulsed neutron beam for in-flight measurements and irradiation stations for cross-section measurements and material studies. Continuous and quasi-monokinetic neutron energy spectra will be available at NFS, produced by the interaction of a deuteron beam on a thick converter and by the (p,n) reaction on a thin converter. The flux at NFS will be up to 2 orders of magnitude higher than those of other existing time-of-flight facilities in the 1 MeV - 40 MeV range. NFS will be a very powerful tool for physics, fundamental research as well as applications like the transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or tests and development of new detectors. Eleven Letters of Intent (LoI) have been submitted to the Scientific Advisory Committee of SPIRAL-2.

2 2 Status of construction 2.1 Buildings The building block that will include the NFS facility is now finished, and the nuclear shaft and cooling circuits are installed. The heavy doors remain to be put in place. The installation of the NFS process is planned to start in Beam line design in the NFS converter room The beam line inside the NFS converter room is completely designed (see Figure 1). With the exception of the magnet and its chamber, which have been delivered, the other components (converter chamber, beam pipes, diagnostic chamber, collimator) have not yet been ordered. Figure 1: 3D view of the complete beam line in the NFS converter room. The clearing magnet has just been delivered (see Figure 2). Recent activation calculations show that this magnet could not be cooled by the secondary circuit dedicated to the magnets and quadrupoles of SPIRAL2. The tritium production rate in the water of the magnet cooling system requires a connection to a ternary circuit. The possibility of cooling the magnet with the cooling system of SAFARI (the LINAC beam dump) is presently under study. Figure 2 : Picture of the clearing magnet of NFS. 2.3 The pneumatic transfer system The pneumatic transfer system will be used for activation measurements. It will transfer samples remotely and rapidly from the irradiation point in the converter room to a detection system in the TOF room. This system

3 allows for irradiation and immediate measurement of samples. Irradiation can be performed with neutrons or with charged particles. In the former, the sample will be placed in air downstream of the converter, in the latter, it will be placed in the irradiation box. The pneumatic transfer system has been built and will be tested at Helmholtz Dresden Rossendorf Zentrum in October Following testing, it will be installed at NPI at Rez (Czech Republic) and connected to the irradiation box under development at NPI. The complete system could be installed at NFS by the end of The converter The production of a high-intensity white spectrum neutron beam at NFS will be obtained by the LINAG deuteron interaction on a thick carbon or beryllium converter. The converter must sustain a power deposition of 2 kw and must be remotely manipulated because of its high activation level. The study and the drawings are performed by the CEA/IRFU in Saclay. The converter design includes the ability to manipulate the rotating wheel into an adapted shielding container for out-of-beam storage. The rotating wheel has been delivered in October 2012 and the first tests of rotation have been performed. It has been verified that the rotation speed is well controlled, and that a control cable of 40 m long is usable and length compatible with the building constraints. Recently, new safety constraints have increased the complexity of the design of the converter. Actually, the control of the target rotation speed is considered as an EPS (element participating to the safety), therefore monitoring should be performed by two independent systems. In such case, the possibility of adding a tachometer on the axis of the rotating wheel is under study. This new parameter makes the design of the system more complex and will delay the construction. 2.5 The second collimator for NFS (IPHC) Some time-of-flight experiments planned at NFS require as low neutron and gamma background as possible. This is the case, for example, of the LoI_Day1_14 experiment which will use a set of germanium detectors to count gamma rays coming from (n,xn) reactions. Following the study already performed for the design of the first collimator at NFS, preliminary simulations (performed with MCNPX code) of the neutron and gamma flux in the experimental room have revealed that the size of the neutron beam is too large ( = 20 cm) at a 20 meter distance from the first collimator exit. A second collimator is thus required to redefine the size of the neutron spot in order to protect the germanium detectors from neutron damage and to reduce the gamma background. Based on its experience with the GELINA neutron beam (IRMM, Geel, Belgium), the GRACE team of the IPHC laboratory has started MCNPX simulations taking into account a second collimator. The optimization of the device is still under progress. 3 The Single bunch selector The Spiral2 linear accelerator works at a frequency of MHz. This value is too high for some time-offlight experiments (F<1MHz), and it is therefore important to have the possibility to reduce the rate of bunches reaching the experimental target. In particular, there is a need to have only one bunch over N (being 100 < N < 10000) with no residual particles from the suppressed bunches. These operations are required since the first experiments and are performed by a medium energy chopper, called the Single Bunch Selector. In the single bunch selector, a static magnetic steerer permanently deviates the bunches onto a dedicated beam-stop while a pulsed electromagnetic wave, traveling on a microstrip meander transmission line, allow the selected bunch to be properly realigned and delivered to the downstream beam line. Main components of the whole device are: the steerer, the pulse generators, the electronics synchronizing the two pulses, the vacuum chamber with the electrodes, and the power loads absorbing the pulses. The device is still under development since it has not yet been possible to find a laboratory to take charge of all the subsystems, therefore they are being studied separately as explained in the following:

4 - Magnet: it has been designed at Ganil and is expected to be ordered and manufactured by December Vacuum chamber and electrodes: an MoU with INFN-LNS (Catania) has been signed to finalize the work begun in the framework of the SP2PP project. This device is expected by April Synchro (and protection) electronics: same MoU with INFN-LNS. Device expected March Load: same MoU with INFN-LNS. Device expected April Pulse generators: available from the Eurisol project but need to be equipped with remote control of the voltage. Manpower for the transformation into remote control not identified - Installation : Manpower for the transformation into remote control not identified 4 R&D for production of radioisotopes 4.1 Study of the production of 99 Mo The production of 99 Mo is of prime interest because it is the principal way to produce 99m Tc, which is the most important radioisotope used in nuclear medicine. Actually, more than 25 million medical diagnostic procedures (more than 80% of all diagnostic procedures) have been carried out worldwide every year using 99m Tclabeled tissue-specific radiopharmaceuticals. Today 99 Mo is produced in reactors by using HEU (highly enriched uranium), with 99 Mo being a fission product. The shutdown of several reactors scheduled in the next few years as well as the increase in 99 Mo demand leads to a search of alternative ways of production. Among the production processes, the 100 Mo(n,2n) 99 Mo reaction seems to be an interesting alternative. The flux at NFS is too low to envisage the production of 99 Mo, however the neutron spectrum having the characteristics of SPIRAL-2, allows a measurement by activation method that could be performed to validate the calculations for 99 Mo production. Figure 3 : 100 Mo(n,2n) 99 Mo cross-section reaction (left scale) and the neutron flux at SPIRAL-2 (right scale). One can conceive that with the higher flux of SPIRAL2-phase2 close to the carbon converter the production of 99 Mo might be possible. The neutron energy spectrum of SPIRAL-2 is well adapted to the cross-section whose maximum is around 15 MeV (see Figure 3). Rough estimations show that SPIRAL-2 could produce 99 Mo with a specific activity about 17 GBq/g after 2 days of irradiation of an enriched 100 Mo sample placed at 10 cm from the converter. This specific activity is several orders of magnitude lower than the one obtained in reactor with HEU. In addition, such production would need a dedicated irradiation station in the production building and an adapted LINAG operating mode. In addition, the expected shortage 99m Tc of In North America, probably will not occur at the European level since the French reactor RJH will produce a large quantity of 99 Mo (10%-20% of world demand) from 2016.

5 4.2 R&D at NFS about new radioisotopes for medicine The R&D about the production method of different radio-isotopes for medicine can certainly be undertaken at the NFS facility. NFS possesses a versatile set-up allowing irradiation of samples with neutron/p/d or heavy ion beam. The local expertise in cross section measurement and high power target can benefit to the field. The R&D about production method of given radio-isotope at NFS facility and the possible production at SPIRAL2 production building (phase 2) are not the only aspect to be considered: target development and chemical separation are of utmost importance. Moreover, the proximity with isotope production lab of CYCERON could help to indentify new opportunities. The industrial production of any radioisotope could not be envisaged at NFS but in a dedicated facility: like CYCERON@Caen, ARRONAX@Nantes or even at SPIRAL2 phase 2 in the future 5 Calculations for safety issues: Several crucial calculations were performed for the completion of the safety file which has to be sent by the end of September. Several technical notes for radioprotection purposes have been written about the activation of material, the water circuit, the residual dose estimations. 6 Adaptation of the GAINS detector GAINS (Germanium Array for INelastic Scattering) is a set-up dedicated to the measurement of (n,n ) crosssection reactions. This detector, presently used at Geel, is composed of 12 high volume HPGe. A new frame is under development to be usable at NFS. The needs of liquid nitrogen as well as the problem of earthquake resistance have been studied. This set-up will be coupled to the GRAPHEME set-up from IPHC. This kind of experiment requires the long flight path of NFS, and will be placed downstream of the second collimator. Figure 4 : The GAINS detector and its new frame designed for the NFS facility. 7 Conclusion The construction of the elements of the NFS process is going on. The construction of the converter and of some NFS components is delayed in respect with the previous planning. However the NFS process will be ready to receive the first beam accelerated by the LINAC by the end of 2014.