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Owada, Hitoshi*; Mihara, Morihiro; Iriya, Keishiro*; *
JNC TN8400 99-057, 43 Pages, 2000/03
Cementitious materials are considered as candidate materials for the geological disposal of high-level radioactive waste and TRU waste. As the pH and the Ca content of leachate from the cementitious materials are high, the host rock and the buffer-material would be degraded by the leachate in the long-term. Therefore, transport properties and parameters such as solubilities and distribution coefficients of radionuclides would be changed and affect the performance of the repository. In order to dissolve this "High pH plobrem", the use of a low alkalinity cement is considered for the disposal. In this study, we summarized the necessity of the low alkalinity cement, and developed the approach of the low alkalinization of cement. And, the following were carried out in this study : A leaching test of cement paste, a fluid test of the mortar and a installation test of the concrete to the trial structure. From the leaching test using the cement paste, we confirmed that we were able to obtain the low alkalinity cement (HFSC) by addition of pozzolanic materials such as silica-fume and flyash. From the result of the fluid test of the mortar, we chose the cement for the practicability evaluation. The practicability of low alkalinity concrete was evaluated by installation test to the trial structure.As a result of these examinations, we proved that the pH value of the leachate from the cementitious material was reduced by adding SF and FA to Portland cement. Simultaneously, SF and FA had to be added in order to obtain the good workability. In addition, workability and mechanical strength of the cement which SF and FA were added are almost equivalent to the ordinary Portland cement. The results shows that the HFSC has high practicability.
Hashizume, Shuji; ; Matsumoto, Junko; Bamba, Tsunetaka
Genshiryoku Bakkuendo Kenkyu, 5(1), p.37 - 44, 1998/08
no abstracts in English
; Aoyama, Makoto; ; Yamanouchi, Takamichi
PNC TN8410 97-319, 143 Pages, 1997/10
The fire and explosion incident occurred at Bituminization Demonstration Facility of PNC Tokai Works on March 11, 1997. In order to ascertain the cause of incident, the investigation has been pushed forward. During investigation, we obtained essential information from operators, such as softness of bituminized product, white smoke generated from bituminized product. This condition has never been observed comparing past normal operation. Therefore, we assumed that temperature of bituminized product had increased more than expected. In order to confirm above assumption, we made experiment for obtaining the relationship between temperature and fluidity of bituminized product. Simulated bituminized product was heated up to each temperature (210, 230, 250, 270
C) in a pot and poured down into an another pot. We observed the fluidity of bituminized product when it flowing down into a pot. The fluidity of bituminized product increased with high temperature. The fluidity of bituminized product at 270C looked similar to fluidity of bituminized product that had ignited itself at the incident. White smoke generated from bituminized product and amounts of white smoke increased with high temperature. The smoke was considered to be gas that generated through thermal decomposition or volatilization of bitumen.
Kawabe, Ryuhei*; Himeno, Yoshiaki; Kawada, Koji*; Miyaguchi, Kimihide
PNC TN941 85-104, 17 Pages, 1985/06
Flow and combustion test of low temperature sodium (250C) on a simulated for liner has been conducted to give an answer to the possible flow blockage or flow plugging. The simulated floor liner used for this purpose was 2.4m in length and 1.2m in width having liner gradient of l/100. The bottom surface of the liner was well thermally insulated. In the test, 160kg of sodium was slowly spilled from a nozzle having a wide opening at flow rate of 1 
/sec for 200 sec. The nozzle was attached to the side of the liner. Flow pattern and combustion characteristics of sodium have been monitored during the test, and temperatures of the flowing sodium and a liner steel have also been measured. In the post-test examinations, distribution of residual sodium and sodium oxide on the floor liner as well as that in a drain pipe was determined. The results thus obtained were summarized as follows. (1)At beginning of the test, although the spilled sodium froze for a certain period of time due to its heat transfer to the liner, it remelted by taking heat from a successive flowing sodium at higher temperature. Therefore, on the liner sodium flowed continuously without being blocked its flow path. (2)Heat flux from sodium to the liner was less than 80kw/m
, while related heat transfer coefficient was 300 
500w/mC. The latter value was almost the same to that obtained from the similar test with hot sodium (505C). (3)Post-test examination revealed that the distribution of residual sodium and sodium oxide on the floor liner was almost uniform with the average value of 1kg/m. No massive combustion products that may cause flow plugging was found in a sodium drain pipe.
Tsunoda, Naomi; Sasaki, Noriaki; Nagaki, Hiroshi
PNC TN841 80-22, 104 Pages, 1980/04
no abstracts in English
Ishii, Katsunori; Segawa, Tomoomi; Kawaguchi, Koichi; Suzuki, Masahiro
no journal, ,
To develop flowability improvement technology for the simplified pelletizing process, a simple granulator with little powder adhesion, was experimentally produced. To know the performance of the granulator, granulation experiments was conducted by using dummy powder.
Ishii, Katsunori; Kawaguchi, Koichi; Segawa, Tomoomi; Suzuki, Masahiro
no journal, ,
JAEA is developing the simplified pelletizing process as advanced MOX fuel fabrication technology in the future. The standardizer could eliminate coarse particles from granules produced by wet granulator without degradation of flowability.
Sato, Ikken; Yoshikawa, Shinji
no journal, ,
In Fukushima Daiichi Nuclear Power Station Units 1-3, some part of the core materials including fuel relocated through the reactor pressure vessel (RPV) into the pedestal area. As a result of comprehensive analysis of data such as pressure gauges and water level gauges,it was evaluated that the time duration of the core material relocation to the pedestal was, less than 0.5 hr for Unit 1, around 2.5 hours for Unit 2 and around 7 hours for Unit 3 respectively.
Osawa, Norihisa*; Kaneda, Yoshihisa*; Sakamoto, Ryo*; Taniguchi, Takumi; Kuroki, Ryoichiro; Osugi, Takeshi
no journal, ,
no abstracts in English
