Experimental studies of passive neutron measurement for fuel debris at Fukushima Daiichi Nuclear Power Plants

Nagatani, Taketeru; Shirato, Atsuhiko*; Kosuge, Yoshihiro*; Sato, Takashi*; Kawakubo, Yoko; Shiromo, Hideo; Asano, Takashi

Proceedings of INMM 56th Annual Meeting (Internet), 10 Pages, 2015/07

As one of the candidate material accountancy technologies for the fuel debris at Fukushima Daiichi Nuclear Power Plants (1F), we propose the application of a passive neutron technique. The applicability of the new concept to the fuel debris at 1F was evaluated by simulation and the results were presented at the last INMM annual meeting. As the next phase, we conducted experimental tests to confirm the validity of the simulation results. Because actual fuel debris or irradiated fuel cannot be handled at our facility due to a licensing limitation, un-irradiated MOX samples, neutron absorbers and Cf-252 sources were utilized as the best available material to imitate the property of the fuel debris and various configurations were measured using an Epithermal Neutron Multiplicity Counter. The fissile mass in the samples, neutron absorber mass surrounding the samples and intensity of Cf-252 source were varied to confirm the correlation between DDSI response and the leakage multiplication. Test results agreed well with the trend of the simulation results. This indicates that DDSI has sufficient capability to evaluate the leakage multiplication of a sample which includes an unknown amount of fissile material and neutron absorber such as the fuel debris at 1F. This paper provides experimental studies of passive neutron measurement based on the combination of DDSI technique and coincidence counting for fuel debris at 1F.

Corrosion evaluation of uranyl nitrate solution evaporator and denitrator in Tokai Reprocessing Plant

Yamanaka, Atsushi; Hashimoto, Kowa; Uchida, Toyomi; Shirato, Yoji; Isozaki, Toshihiko; Nakamura, Yoshinobu

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 6 Pages, 2011/12

The Tokai Reprocessing Plant (TRP) adopted the PUREX method in 1977 and has reprocessed spent nuclear fuel of 1140 tHM (tons of heavy metals) since then. The reprocessing equipment suffers from various corrosion phenomena because of high nitric acidity, solution ion concentrations, such as uranium, plutonium, and fission products, and temperature. Therefore, considering corrosion performance in such a severe environment, stainless steels, titanium steel, and so forth were employed as corrosion resistant materials. The severity of the corrosive environment depends on the nitric acid concentration and the temperature of the solution, and uranium in the solution reportedly does not significantly affect the corrosion of stainless steels and controls the corrosion rates of titanium steel. The TRP equipment that handles uranyl nitrate solution operates at a low nitric acid concentration and has not experienced corrosion problems until now. However, there is a report that corrosion rates of some stainless steels increase in proportion to rising uranium concentrations. The equipment that handles the uranyl nitrate solution in the TRP includes the evaporators, which concentrate uranyl nitrate to a maximum concentration of about 1000 gU/L (grams of uranium per liter), and the denitrator, where uranyl nitrate is converted to UO powder at about 320C. These equipments are therefore required to grasp the degree of the progress of corrosion to handle high-temperature and high-concentration uranyl nitrate. The evaluation of this equipment on the basis of thickness measurement confirmed only minor corrosion and indicated that the equipment would be fully adequate for future operation.

Applicability of coal ash (fly ash) to high strength shotcrete

Orukawa, Go; Kojima, Wataru; Shirato, Nobuaki*; Saito, Toshiki*

Konkurito Kogaku Nenji Rombunshu (DVD-ROM), 28(1), p.1637 - 1642, 2006/00

no abstracts in English

Support design study for the Horonobe underground research facility in FY2003/2004

Matsui, Hiroya; MORIOKA, Hiroyuki; Shirato, Nobuaki; Ouchi, Kazutoshi

JNC TN5410 2004-001, 236 Pages, 2004/08

JNC-TN5410-2004-001.pdf:22.79MB

JNC(Japan Nuclear Cycle development institute) has been conducting the project called "Horonobe URL project" in Horonobe-cho, Hokkkaido, Japan. The aim of the project is to establish the scientific and technical basis for geological disposal on sedimentary rock. In the project, a underground facility with 500m depth will be constructed. This report is summarized the results on support design of the planned underground facility based on the data obtained by the several borehole investigations from ground surface. Owing to rational support design, the detailed compartment of the input parameters for the stability analysis in surrounding rock at position of underground facility were made based on the results of borehole investigation in HDB-1, HDB-3, which were drilled near the position. Moreover, the idea of double support system was adopted in this study to minimize the support in underground facility.

Feasibility study on construction of Horonobe URL

Shirato, Nobuaki; Ouchi, Kazutoshi; Yamazaki, Shinichi

JNC TN5400 2004-002, 485 Pages, 2004/08

JNC-TN5400-2004-002.pdf:1.07MB

The Horonobe underground Research Laboratory (URL) programme hosted by sedimentary rocks is aimed to obtain deep geological characteristics of sedimentary rock mass and to confirm the applicability of the investigation methods for the geological environment and the engineering technology for the geological disposal described in the H12 report. In addition, the URL is aimed to have public people experience a deep geological environment in order to understand a deep geological disposal of HLW. The objective of this report is to make the ground of the site selection of the Horonobe URL Based on the results obtained from two deep investigation boreholes drilled in the B1 and B2 district two kinds of geological model were constructed. For each geological model four types of preliminary layout were prepared for the feasibility study. The types of the URL were as follows: (i)two shafts (ii)three shafts (iii)spiral drift and one shaft (iv)spiral drift and two shafts. For the combination of the geological model and the layout tbe construction schedule and the construction cost were estimated through the study of the construction method with the auxiliary method, the construction procedure and the cycle time. The analysis of vibration and noise during construction was also estimated. The results of the feasibility study indicated that mechanical excavation was employed for the whole construction. The shafts were suggested to be constructed by the short step sinking method and the drifts and the spiral drifts by NATM. The mucking system should be rail haulage for the drift for the case of shafts(i) and (ii)), and road haulage for the drift for the case of spiral drifts(iii) and (iv)). The estimation of construction time was around seventy months for the case of shafts(i) and (ii)) and around ninety months for the case of spiral drifts(iii) and (iv)). This work was re-edited from the results performed by Taisei Corporation under contract with JNC; "Feasibility study on ...

Underground Research Laboratories for R&D on HLW

Sato, Toshinori; Shirato, Nobuaki

Tunneling Activities in Japan 2014, P. 24, 2004/00

no abstracts in English

None

; Nakatsuka, Noboru; Eki, Nobuhiro; ; Takeuchi, Ryuji; ; Shirato, Nobuaki

JNC TN1400 2002-017, 31 Pages, 2002/06

JNC-TN1400-2002-017.pdf:7.62MB

no abstracts in English

Development of economy estimation system for FBR - phase II; Study on capital cost assessment method phase II

*; *; Shirato, Seiichi*; *; Nakanishi, Seiji; *

PNC TN9410 88-177, 340 Pages, 1988/09

PNC-TN9410-88-177.pdf:21.32MB

This report summarized the results of the study on the capital cost assessment methods in FY1987 which is one of the economic estimation system for FBR that had been developing from FY1986. In this study, the assessment methods developed in FY1986 were investigated in more detail concentrating on equipments and components peculiar to FBR. Moreover, the Land, Structure and Building which compose the capital cost were modeled to be able to calculate the total capital cost. The results of this study are as follows. (1)Investigation of the assessment model for equipments and components peculiar to FBR The assessment methods for equipments and components peculiar to FBR which extracted in FY1986 were evaluated in more detail. Thus, the cost is assessed as the accumulation of the materials and manufacturing cost of the equipments and components in principle. (2)Land, Structure and Building cost model. The cost assessment model for the FBR buildings was determined based on the cost of the total area of the buildings which estimated in reference to the investigation of the materials of LWR (PWR). On the other hand, the model for the Land and Structures was used as the same model as that of LWR. (3)Trial cost estimation of 1000MW FBR plant. The capital cost of 1000MW FBR plant except some facilities which the materials and specifications are unknown was estimated for trial using both the assessment methods developed in FY1986 and 1987. (4)Preparation of the data base of the economic estimation system for the advanced LWR. With regard to the Advanced PWR and BWR which chose as the subject of the economic estimation for FBR considering the phase of commercial FBR deployment, important improvements and differences from the present LWR design were summarized from the view point of the cost estimation and were prepared for the data base of the Advanced LWR. In the future, the capital cost assessment methods developed in this study will be coded to be easily use and ...

Experiments on the water leak detection system in the 50MW steam generator test facility (13); Data of water leak simulation tests

Kaneko, Yoshihisa*; Nishikimi, Masakazu*; Shirato, Seiichi*; Morimoto, Makoto*; *

PNC TN941 85-24, 194 Pages, 1985/02

PNC-TN941-85-24.pdf:10.16MB

Series of tests on the water leak detection system have been conducted in the 50MW Steam Generator Test Facility since December 1974. This report is data of water leak simulation tests (water or hydrogen injection tests) which were carried out until November 1983 since May 1978. These data (response of water leak detector) are recorded in magnetic tape and it is easy to change scale and soon.

Experiments on the water leak detection systems in the 50MW steam generator test facility (9); Cold trap efficiency test, hydrogen background concentration test, hydrogen flux through tube test

Kaneko, Yoshihisa*; Nishikimi, Masakazu*; Shirato, Seiichi*; *

PNC TN941 85-22, 142 Pages, 1985/02

PNC-TN941-85-22.pdf:3.57MB

Series of tests on water leak detection system for Monju steam generators have been excuted in the 50MW Steam Generator Test Facility (50MW SGTF). This paper describes the test results about the removal efficiency of hydrogen by the secondary cold trap, the hydrogen background concentration and hydrogen flux through heat transfer tubes to secondary sodium in steam generator (SG) in order to make clear the hydrogen behavior during ordinary plant operation from October in 1976 to July in 1983. Main results from these tests are: (1)The removal efficieney of hydrogen by the cold trap is 7080 percents, but it shows tendency to decrease when difference between hydrogen concentration at cold trap and that in secondary main loop is small. (2)Hydrogen flux through tubes is smaller than the value which is reported in the first report of these series reports. (3)It is found that the hydrogen background concentration in the secondary main loop of 50MW SGTF is thoroughly low. (4)It is estimated that the hydrogen background concentration in the secondary main loop in Monju plant is lower than 169 ppb.