A Review of revaporisation behaviour of radioactive Cs deposits and its impact on the source term in severe nuclear accidents from Phbus FP results and single effect testing

Knebel, K.*; Jokiniemi, J.*; Bottomley, D.

Journal of Nuclear Science and Technology, 56(9-10), p.772 - 789, 2019/09

https://doi.org/10.1080/00223131.2018.1558130

Revaporisation of the fission products deposited in the primary circuit of a reactor was identified as a possible late source of fission product release during a severe accident: eg. loss of coolant accident (LOCA). Subsequent testing has shown that revaporisation is very likely to occur given a breach of the reactor and is an important contributor for the source term release to the containment and biosphere. The first part reviews the revaporisation mechanisms of Cs and other volatile or semi-volatile fission products transported in the primary circuit that were derived from the Phebus FP and associated programmes. The second part examines the separate effects testing to determine the high temperature chemistry ofvolatile and semi-volatile fission products (I, Mo, Ru) and structural materials (Ag, B) as well as atmospheric effects which substantially affect the source term. Finally, it examines Cs data from reactor accident sites that is providing additional knowledge of longer-term fission product chemistry. The results have been summarised in the form of a table and schematic diagram. This accumulated knowledge and experience has important applications to minimising contamination during decommissioning and site remediation techniques, as well as improving SA simulation codes and raising nuclear safety.

Current status of research for the accident of evaporation to dryness caused by boiling of reprocessed high level radioactive liquid waste

Tamaki, Hitoshi; Yoshida, Kazuo; Abe, Hitoshi; Sugiyama, Tomoyuki; Maruyama, Yu

Proceedings of Asian Symposium on Risk Assessment and Management 2017 (ASRAM 2017) (USB Flash Drive), 9 Pages, 2017/11

An accident of evaporation to dryness caused by boiling of high level radioactive liquid waste (HLLW) is postulated as one of severe accidents caused by the loss of cooling function at the fuel reprocessing plant. This accident can be divided into early boiling stage, late boiling stage and dry-out stage by characteristics of accident evolution. It is important to estimate the amount of fission product (FP) transport between the liquid and gas phases, and the amount of FP deposition on the walls in each stage in order to estimate the release amount of FP to the environment. Various research activities have been carried out for this issue. This paper reviews these activities and presents the recent activities at JAEA for development of simulation code for this type of accident.

Development of Ru transfer rate correlation to vapor phase in accident of evaporation to dryness by boiling of reprocessed high-level liquid waste

Yoshida, Kazuo; Tashiro, Shinsuke; Amano, Yuki; Yamane, Yuichi; Uchiyama, Gunzo; Abe, Hitoshi

Nihon Genshiryoku Gakkai Wabun Rombunshi, 13(4), p.155 - 166, 2014/12

https://doi.org/10.3327/taesj.J14.010

An accident of evaporation to dryness by boiling of high level liquid waste (HLLW) is postulated as one of the severe accidents to occur caused by the loss of cooling function at a fuel reprocessing plant. In this case, a large amount of ruthenium (Ru) will be volatilized and transfer to the vapor phase in the tank, and could be released to the environment. Therefore, the quantitative estimation of released Ru is one of the key issues in the assessment of the accident consequence. To resolve this issue, an empirical correlation for Ru transfer rate to vapor phase with the temperature, nitric acid mol fraction and activity of HLLW has been developed based on the data obtained from the accelerated experiments using simulated HLLW. A simulation study with the developed correlation demonstrated that amount of Ru transfer to vapor phase was in a good agreement with the long term experiment using actual HLLW.

Toward a robust phenomenological expression of evaporation efficiency for unsaturated soil surfaces

Komatsu, Teruhisa; Adachi, Takeo

Journal of Applied Meteorology, 42(9), p.1330 - 1334, 2003/09

no abstracts in English

Effect of shell structure in the fusion reactions Se+Ba and Se+Ba

Sato, Kenichiro; Ikezoe, Hiroshi; Mitsuoka, Shinichi; Nishio, Katsuhisa; Jeong, S.-C.*

Physical Review C, 65(5), p.054602_1 - 054602_9, 2002/05

https://doi.org/10.1103/PhysRevC.65.054602

no abstracts in English

Evaporation speed of water from various soil surfaces under calm state

Komatsu, Teruhisa

Journal of the Physical Society of Japan, 70(12), p.3755 - 3756, 2001/12

https://doi.org/10.1143/JPSJ.70.3755

no abstracts in English

Manufacture of ultrasonic thickness measurement apparatus

Oba, Toshihiro; Yanagihara, Takao; Kato, Chiaki; Hamada, Shozo

JAERI-Tech 2001-059, 36 Pages, 2001/09

JAERI-Tech-2001-059.pdf:7.8MB

The demonstration test for evaluating reliability of the acid recovery evaporator at Rokkasho Reprocessing Plant has been carried out at JAERI. For the nondestructive mesurement of the thickness of heat transfer tubes in the acid recovery evaporator and short tubes used in corrosion test, we have developed ultra sonic thickness measuring apparatus using immersion method with high resolution. This apparatus can measure and record tube thickness automatically with a personal computer. The results obtained by this apparatus are coincident with the results obtained by a destructive method using an optical microscope.

Long-term durability test of acid recovery evaporators made of Ti-5% Ta aIloy and zirconium

; Fujisaku, Kazuhiko*; *; ; Koyama, Tomozo

JNC TN8410 2001-013, 255 Pages, 2001/05

JNC-TN8410-2001-013.pdf:24.24MB

Mock-ups of acid recovery evaporators which are made of Ti-5% Ta alloy and Zr were tested under inactive condition for forty thousands hours to improve a corrosion resistance of acid recovery evaporator in Tokai reprocessing plant (TRP). The mock-up unit was designed and produced referring to the specification of acid recovery evaporator in TRP and the evaporation performance of the mock-up was 1/27 of TRP. A long-term durability of both evaporators was demonstrated by results of operation data, evaporation performance and corrosion resistance. The mock-up unit did not suffer from any trouble during the running test and the operation data such as temperature, flow, concentrations of nitric acid and metal ions were fairly stable within standard condition. As for the corrosion resistance, cracks and local corrosion such as intergranular attack were not observed on both evaporators after the running test, and a corrosion of weld was not selective. The average corrosion rates at measuring points were less than 0.1mm/yr, respectively, however, thickness of the Ti-5% Ta alloy evaporator was slightly reduced at all points of vapor phase region. In addition, from the result by test coupon, it is found that both materials have low susceptibility to stress corrosion cracking in this environment. The destructive inspection showed that the mechanical properties of both materials were not degraded during the running test. Finally, the total running time of the mock-up unit is much more than a maximum running time of acid recovery evaporator made of stainless steel in TRP (nearly 15,000 hours). On the basis of the test results, an excellent durability of Ti-5% Ta alloy and Zr evaporators under was successfully demonstrated throughout the mock-up test from an engineering perspective.

Improvement effect on corrosion under heat flux on nitric acid solutions of anti-IGC stainless steel and high Cr-W-Sr Ni base alloy

Doi, Masamitsu; Kiuchi, Kiyoshi; Yano, Masaya*; Sekiyama, Yoshio*

JAERI-Research 2001-020, 17 Pages, 2001/03

JAERI-Research-2001-020.pdf:0.7MB

no abstracts in English

Silicon plate penetration with a high energy laser pulse

Nishimura, Akihiko; Usami, Tsutomu*; Deki, Kyoichi*; Shimobeppu, Y.*; Hayasaka, N.*; Arisawa, Takashi

Technical Digest on 4th Pacific Rim Conference on Lasers and Electro-Optics (CLEO/Pacific Rim 2001), p.II_280 - II_281, 2001/00

no abstracts in English