1. Centrum vyzkumu Rez
CZECH COUNTRY REPORT PART II: LVR-15 REACTOR OPERATION AFTER HEU - LEU CONVERSION - IRRADIATION TEST PROJECT
Jiri Rychecky
05 June 2013
2. 1
CZECH COUNTRY REPORT: LVR-15 IRRADIATION TEST PROJECT - Introduction Only the LEU fuel is used for reactor operation since September 2011. The purpose of this test project is to demonstrate that the new LEU converted reactor core is able to irradiate LEU vs. HEU materials and samples, a key capability for future use of the research reactor. 20 operational cycles were performed since Sept. 2011 with various core configurations Production of NTD Si ingots have been increased more than two times - the second NTD facility was installed on Jan.2013. Irradiation of U targets for Mo production also increased more than two times due the HFR Petten is temporarily shut down. Two rigs with samples for material testing were irradiated.
4. Irradiation and Experimental Facilities The following irradiation and experimental facilities were in operation on 2012 - 2013 Pneumatic rabbit system for activation analyses 2 facilities for Si NTD (new one was installed on Jan. 2013) 2 irradiation rigs for material testing probes 3 vertical irradiation channels for production of radioactive isotopes (Ir, Sm, etc.) at peripheral positions 6 neutron beams (horizontal channels) for physical research Experiments for BNCT on thermal column Up to 4 irradiation channels for irradiation of U targets for Mo99 production inside the central neutron trap 2 irradiation channels inside Be for irradiation of Ir targets
5. Sept. 2011- K132 start LEU, Jan. 2012 – TW3 Rig
10
9
8
7
6
5
4
3
2
1
A B C D E F G H
core_layout ern@cvrez.cz
B
B
B B
B B
B
B
B
B PR
B
B B
B
B B
B
B
B
02 03 01 12 09
08
11
10
05 04 06 07
Ir
Ir
B void
B
10
9
8
7
6
5
4
3
2
1
A B C D E F G H
core_layout ern@cvrez.cz
B
B
B
B
B
B
B
B
B
B PR
B
B
B B
B
B
B
B
B
02 03 01 12 09
08
11
10
05 04 06 07
Ir Ir
B B void
EFDA
TW3
Si
void void
6. June 2012 -K143, Dec. 2012 - K147 – NTD Si, Mo
10
9
8
7
6
5
4
3
2
1
A B C D E F G H
core_layout ern@cvrez.cz
B
B
B
B
B
B
B
B
B
B PR
B
B
B
B
B B
B
B
B
02 03 01 12 09
08
11
10
05 04 06 07
Ir
B void
B
EFDA
TW3
Si
Ir
II
I 0
7. Jan. 2013 - K148 - 2 Si+Mo, May 2013 - K150 – BNCT + Ir
10
9
8
7
6
5
4
3
2
1
A B C D E F G H
core_layout ern@cvrez.cz
B
B
B
B B
B
B
PR
B
B
B
B
B
02 03 01 12 09
08
11
10
05 04 06 07
Ir
Ir
B
B
B
B
B
B
B
B B void
SPND
DN 3"
SPND
DN 4"
void
II II
II II
10
9
8
7
6
5
4
3
2
1
A B C D E F G H
core_layout ern@cvrez.cz
B
B
B
B B
B
B
PR
B
B
B
B
03 01 09
08
11
10
05 04 06 07
Ir Ir
B
B
B
B
B B
B void
B
B
02 12
B
0
0
0
void void
SPD
SPND
DN3"
SPND
DN4"
8. Conclusions During the reactor operation the condition of the fuel gladding was performed. The samples of the primary water were used for checking of non leakage of the fuel assemblies. No leakage of the fission products was detected. The measurement of gas releases from ventilation chimney also was deeply below limits as well. The manipulation with the IRT-4M FAs was without problems. But the manipulation has to be performed carefully because the cladding of the fuel is very thin. The regular operation of the reactor LVR-15 with LEU was continued on 2012 - 2013. Experiences gained more than 1.5 year of operation showed that the LVR-15 operation with LEU cores is possible and the impacts are not so high except economical impacts.
9. Conclusions
Thermal neutrons flux was decreased about 7-10% on started configuration with fresh fuel, but another 10% is decreasing when the average burn was higher Fast neutrons flux will decrease for 5 %. It is possible to cancel losses of thermal neutrons by making neutron traps and/or increasing reactor power by 20%. At present research is carried out on improvement of reactor parameters, and magnification of a thermal neutrons flux.
11. Beam Tubes and BNCT Facility
Introduction Horizontal channels generally represent one of major reactor LVR-15 utilization (their spatial disposition is visible on Fig. 2). BNCT Facility of the LVR-15 research reactor is a facility intentionally built for the development of a Boron Neutron Capture Therapy method, which is aimed at the treatment of a glioma type brain tumor. The facility consists of a neutron horizontal beam with Al and AlF3 filters (collimators), irradiation chamber and control room (see Fig. 3 and Fig. 4). The scheme of the BNCT channel can be found on Fig. 1. The whole facility is still regularly used, although medicinal research at the LVR- 15 reached its peak during 2001 when five patients were irradiated as a part of clinical trial.
12. Fig. 1 Horizontal Channels on LVR-15
powderdiffractometerdepth profilingn- capturestrain scannerinterferometerboron capture therapySANS texturediffractometer102 m stress/straindiffractometer
14. Experiments on BNCT Facility At present, medicinal research at the BNCT beam is aimed at study of boron deposition inside the tumor cells. Effectiveness of different boron compounds is investigated and experiments usually include works with living animals (young laboratory rats) and tissue samples. Also, the beam is used mostly as a source of neutrons for detector testing or material irradiation, beside the medicinal research. The non-medicinal activities are more important during several last years
17. A typical spectrum for the former HEU core is visible on the BNCT horizontal beam
BNCT NRI Beam, 14.08.20011.E+051.E+061.E+071.E+081.E+091.E-081.E-071.E-061.E-051.E-041.E-031.E-021.E-011.E+001.E+01Energy [MeV] Neutron Fluence Rate per Unit of Lethargy [1/cm^2s] STAYSLSANDCalculationBASACFMCNP 0 cm orig. spectrum HoIn3fMCNP 0 cm opr. spectrum HpIn3f
18. Experiments on BNCT Facility (2) The question of the impact of HEU to LEU transition to beam energy spectrum and neutron fluence rates is very important for the Research Centre Rez, because the information about real dose, which irradiated sample (material) received, is necessary for proper experiment evaluation. Most of the time, it is also requested by customers before any official cooperation can even start.
20. Irradiation of rats on BNCT Epithermal Beam Six day-old rats were used as biological models. Sodium borocaptate (BSH, 100 μg 10B/g b.w.) was injected into forebrain ventricles. 10B-phenylalanine-fructose complex (BPA) was applied subcutaneously. Both 10B carriers were from Katchem, Prague. Animals were irradiated in a polyethylene holder (Fig. 8) for 5 to 7.5 min and were sacrificed anesthetized by CO2 enriched atmosphere 8 hours or 3 days later. The experiments were carried out in compliance with EU and Czech legislation for animal protection. The brain and intestine were processed by routine histological protocol and examined microscopically.
22. Conclusion - BNCT horizontal beam Operation of BNCT epithermal beam and results of the BNCT beam measurement demonstrated, that the transition from HEU enrichment to LEU enrichment brought no significant change, which would require doing countermeasures. The results reveal that the conversion of the reactor has only minor influence on the spectral parameters of the beam and on the beam intensity as well. The very important fact is that active core K141 was not only first LEU core designed for BNCT, but also a first BNCT LEU core with installed central trap for molybdenum production. Ability to simultaneously operate epithermal beam and central trap further increases flexibility of the reactor LVR-15 utilization.
23. Conclusions - Final Results of our experience show that IRT-4M type FA is quite good and the fuel is reliable for LVR-15 operation but maybe it is not the optimal low enriched fuel suitable especially for economical reasons. As U9MoAl fuel has higher density (5,40 g/cm3), than UO2-Al (2,51 g/cm3 ), then active core could be compiled compact and neutron flux will not decrease compared to HEU core In connection with this, relevance of research works of UMo, or other types of low enriched on U-235 fuel for the research reactors remain. Additional losses of thermal neutrons (10-20%) are expecting after conversion of the HEU targets for Mo production
24. Conclusions - Final Shortcoming of low enriched IRT-4M type FA is its smaller inserted positive reactivity at replacement of burnt FA with a fresh one and relative low U-235 burn up - IRT-2M type FA U-235 burn up could reach 65 %, compare IRT-4M - 45% - 50%. IRT-4M fuel using leads to increase the price of the FA by factor 3. So, the budget for new fuel could be too high for reactor operation from economical point of view in next years. The next increasing of the financial demands will be also when the reactor power would be risen up to 12 MW. So, we can solve the technical impacts of the conversion, but we will have difficulties to solve the economical one.
25. Looking into the future Reactor power increasing up to 12 MW (2013) Refurbishment of the I & C system (2013) Conversion of the HEU targets for Mo production to LEU one (2014 - 2015 ) Funding of the LVR-15 operation – looking for the new sources and new projects (high temperature loops, irradiation for fusion etc.)
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