{"created":"2023-06-20T13:20:30.518413+00:00","id":535,"links":{},"metadata":{"_buckets":{"deposit":"1b03634d-1800-48b8-bc85-982873504ed1"},"_deposit":{"created_by":1,"id":"535","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"535"},"status":"published"},"_oai":{"id":"oai:ir.soken.ac.jp:00000535","sets":["2:427:12"]},"author_link":["0","0","0"],"item_1_creator_2":{"attribute_name":"著者名","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"栗, 再新"}],"nameIdentifiers":[{}]}]},"item_1_creator_3":{"attribute_name":"フリガナ","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"リ, ツァイシン"}],"nameIdentifiers":[{}]}]},"item_1_date_granted_11":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2007-09-28"}]},"item_1_degree_grantor_5":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"総合研究大学院大学"}]}]},"item_1_degree_name_6":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（工学）"}]},"item_1_description_12":{"attribute_name":"要旨","attribute_value_mlt":[{"subitem_description":" Self-cooled Li and Flibe blankets with V-alloy structure are attractive
concepts and considered for the LHD-type helical fusion reactor design
FFHR. Maximum thickness allowed for blanket is 1.2 m in FFHR. Blanket
functions such as heat removal due to 14 MeV D-T fusion neutrons, breeding
of tritium fuel and radiation shielding must be fulfilled within this thickness.
To verify blanket functions, detailed neutronics investigations are
required. One of the key options for Li and Flibe blankets is the use of
neutron multiplier Be because, in spite of potential benefit of Be from
neutronics aspects, there are some issues specific to Be such as irradiation
effects. Thus it is necessary to evaluate quantitatively the impact of Be on
tritium breeding ratio (TBR), radiation shielding and radio activation. For Li
blanket, it is necessary to apply an electrical insulating coating e.g. Er2O3, to
reduce the magnet-hydro dynamic (MHD) pressure drop when Li flows in a
strong magnetic field. However, neutronics investigation on the effect of
Er2O3 is scarce.
To provide the reactor design with viable data, the neutronics analysis
procedure including transport and activation codes and nuclear libraries
applied to liquid blankets need to be examined and, if necessary, improved.
For this purpose, benchmark studies with systematic comparison of
calculations and experiments are necessary.
The objectives of the present study are:
To investigate Li and Flibe blankets for FFHR by neutronics analysis
with focus on the effect of Be and Er2O3 coating on TBR, shielding and
activation.
To examine or improve the neutronics calculation procedure for
application to liquid blankets by comparison with activation experiments
using D-T neutrons.
In the neutronics assessment of FFHR, 3 dimension Monte Carlo code
MCNP-4C with JENDL3.2 pointwise nuclear data file and FISPACTL2001
code with EAF-2001 file in 175 energy groups were used for neutron
transport and activation calculations, respectively. The results obtained are
qualitatively assumed as follows: Use of Be can significantly improve TBR
for both Li/V-alloy and Flibe/V-alloy blankets. For the Li/V-alloy blanket with
Be, the shielding property can be greatly improved maintaining the adequate
TBR. On the other hand, the shielding property of the Flibe/V-alloy blankets
with and without external Be is comparable. The quantitative estimate of
the effects of Er2O3 coating showed that the activation of the coating could
influence, the long-term activation property of the structural components.
However, recycle of materials for the structural components is still feasible
with Er2O3 coating in 10μm thickness. With 1μm thickness of the coating,
the activation level of the blanket is close to the hands-on recycling limit.
For the purpose of verifying or improving the neutronics calculation
procedure, especially activation analysis of liquid blankets, a series of
irradiation experiments were performed using Fusion Neutronics Source
(FNS) at Japan Atomic Energy Agency (JAEA), which is well-suited to
neutronics study relevant to a D-T fueled reactor. The specimens of
V-4Cr-4Ti, Er and Teflon in 10 mm×10 mm×0.03-0.1 mm were prepared for
studying the activation of V-alloy structure, MHD coating of Er2O3, and F in
molten salt Flibe, respectively. In addition to the assembly for direct D-T
neutron irradiation, Be, Li and Li/Be mock-ups were assembled to examine
the dependence of the activation on neutron spectrum expected in fusion
blankets.
The activities of specimens measured with a high purity Ge detector
were compared with the calculations using FISPACT-2001 codes and
EAF-2001 file. The neutron flux calculated by MCNP-4C was used as input
file in FISPACTL-2001 calculation. In this study, the continuous-energy
cross-section data were also used in activation calculation in the limited
cases in addition to the data of EAF-2001 in 175 and 315 energy groups.
Comparison of calculation (175 groups) to experiment (C/E) shows that
the values of C/E for most of radioactive nuclides (18F, 48Sc, 161Er, etc)
produced by reactions with high-energy threshold lie in the range of 0.8-1.2.
A significant underestimation for 168Ho (C/E 0.62) was found in D-T neutron
irradiation case. It could be caused by the effects of coarse energy grouping
near 14 MeV because 168Er(n,p)168 Ho has a threshold energy close to 14 MeV
and its cross-section rises steeply around 14 MeV. In fact, the C/E value of
168Ho calculated with continuous-energy cross-section approached unity.
The comparisons of activation for 171Er and 52V, both of which are the
products of (n, Υ) reactions, were performed with activation data in 175, 315
energy groups and continuous data. For 52V, the major contribution is the
reaction with thermal neutrons. Using 315 group cross sections, C/E values
of 52V show a clear trend approaching to unity relative to those using 175
energy groups case because of the finer group structures in thermal neutrons
range. The results also agree well with the results using the
continuous-energy cross section. The reaction 170Er(n, Υ)171Er has a huge
resonance peak at 95 keV. Large overestimations for 171Er were observed
with group data due to the coarse grouping in the resonance region. Use of
continuous-energy cross-section provided much better agreement with
experiment for Be mock-up, where the neutron flux is almost constant with
energy in the resonance range. On the other hand, for the case of Be/Li
mock-up, where the flux rapidly increases with energy in the resonance
range, large discrepancy (C/E 〜1.17) was observed even with continuous
cross-section. This result clearly indicates the necessity for re-evaluation of
the cross-section data of 170Er(n, Υ)171Er reaction. This issue was disclosed
though the comparative examination of C/E in various neutron spectra, and
thus unique achievement of this study.
Conclusions of the present study are:
A) Detailed neutronics characterization of Li and Flibe blankets using
V-alloy structure for FFHR has, for the first time, been carried out:
A-1) Advantage of the use of Be is quantified. With Be, TBR design margin
for Li and Flibe blankes could be improved. For Li blanket with Be, the
shielding design margin could also be improved with adequate TBR. The
results provide information necessary for characterizing trade-off of using
Be in Li and Flibe blankets.
A-2)The Er2O3 coating induces the long-term radioactivity of Li blanket.
However, recycle of structural materials is still feasible with Er2O3 coating
in 10μm thickness. Thinner Er2O3 coating is necessary for realizing
hands-on recycling.
B) Experimental studies of activation characteristics for materials in Li and
Flibe blankets have been carried out using a D-T neutron source, especially
for the first time for the Er2O3 coating:
B-1) For the threshold reactions, where the threshold energy is close 14 MeV
and its cross-section rises steeply around 14 MeV, continuous-energy
cross-section data is needed.
Be2) For the (n, Υ) reaction with high cross-section at thermal neutrons
region, finer grouping is necessary.
B-3) Use of continuous-energy cross-section is necessary for (n, Υ) reaction
with dominant resonance peak in medium energy ranges.
B-4) The cross section data of 170Er(n, Υ)171Er needs re-evaluation.","subitem_description_type":"Other"}]},"item_1_description_7":{"attribute_name":"学位記番号","attribute_value_mlt":[{"subitem_description":"総研大甲第1089号","subitem_description_type":"Other"}]},"item_1_select_14":{"attribute_name":"所蔵","attribute_value_mlt":[{"subitem_select_item":"有"}]},"item_1_select_8":{"attribute_name":"研究科","attribute_value_mlt":[{"subitem_select_item":"物理科学研究科"}]},"item_1_select_9":{"attribute_name":"専攻","attribute_value_mlt":[{"subitem_select_item":"10 核融合科学専攻"}]},"item_1_text_10":{"attribute_name":"学位授与年度","attribute_value_mlt":[{"subitem_text_value":"2007"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"LI, Zaixin","creatorNameLang":"en"}],"nameIdentifiers":[{}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲1089_要旨.pdf","filesize":[{"value":"358.4 kB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"要旨・審査要旨","url":"https://ir.soken.ac.jp/record/535/files/甲1089_要旨.pdf"},"version_id":"fd2a4690-e0c8-4b00-b275-fd418955b95c"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲1089_本文.pdf","filesize":[{"value":"2.9 MB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"本文","url":"https://ir.soken.ac.jp/record/535/files/甲1089_本文.pdf"},"version_id":"976f5114-984f-436a-baad-9abd1c33dfb3"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"Benchmark study on neutronics performance of liquid blankets","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Benchmark study on neutronics performance of liquid blankets"},{"subitem_title":"Benchmark study on neutronics performance of liquid blankets","subitem_title_language":"en"}]},"item_type_id":"1","owner":"1","path":["12"],"pubdate":{"attribute_name":"公開日","attribute_value":"2010-02-22"},"publish_date":"2010-02-22","publish_status":"0","recid":"535","relation_version_is_last":true,"title":["Benchmark study on neutronics performance of liquid blankets"],"weko_creator_id":"1","weko_shared_id":1},"updated":"2023-06-20T16:01:25.767275+00:00"}