Raw Materials for Low-Activation Concrete Neutron Shields.

Kinno, M.; Kimura, Ken‐ichi; Nakamura, Takashi

doi:10.3327/jnst.39.1275

Cited by 10 publications

(9 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We assumed the 30-year operation for estimation of the residual activity in the concrete concerning the safety aspects, since because a cyclotron is usually operated for about 10–20 years. We estimated the radioactivity of 60 Co, 134 Cs, 152 Eu, and 154 Eu as the resulting long-lived radionuclides [ 14 – 16 ]. These radionuclides with a long half-life and high cross section are important in decommissioning.…”

Section: Methodsmentioning

confidence: 99%

Radiologic assessment of a self-shield with boron-containing water for a compact medical cyclotron

Horitsugi

Yamaguchi

Eto

et al. 2012

Radiol Phys Technol

View full text Add to dashboard Cite

The cyclotron at our hospital has a self-shield of boron-containing water. The amount of induced radioactivity in the boron-containing water shield of a compact medical cyclotron has not yet been reported. In this study, we measured the photon and neutron dose rates outside the self-shield during cyclotron operation. We estimated the induced radioactivities of the boron-containing water used for the self-shield and then measured them. We estimated the activation of concrete outside the self-shield in the cyclotron laboratory. The thermal neutron flux during cyclotron operation was estimated to be 4.72 × 102 cm−2 s−1, and the activation of concrete in a cyclotron laboratory was about three orders of magnitude lower than the clearance level of RS-G-1.7 (IAEA). The activity concentration of the boron-containing water did not exceed the concentration limit for radioactive isotopes in drainage in Japan and the exemption level for Basic Safety Standards. Consequently, the boron-containing water is treatable as non-radioactive waste. Neutrons were effectively shielded by the self-shield during cyclotron operation.

show abstract

Section: Methodsmentioning

confidence: 99%

Radiologic assessment of a self-shield with boron-containing water for a compact medical cyclotron

Horitsugi

Yamaguchi

Eto

et al. 2012

Radiol Phys Technol

View full text Add to dashboard Cite

show abstract

“…6 They found that a longer operation period resulted in more radionuclides with longer, rather than shorter half-lives. 6 Therefore, the generated radionuclides and their radioactivity concentrations depended on the energy of accelerated particles, 23 atomic composition 24 and the durations of the operating and cooling periods. [6][7][8]25 The maximum amount of concrete estimated as radioactivated waste in the present study was 70,000 kg.…”

Section: Discussionmentioning

confidence: 99%

“…8 The use of concrete with less Co and Eu than ordinary concrete could reduce the amount of radioactivated materials. 24 The production of radioactivated materials is not inhibited when using an unshielded cyclotron. A method using an additional shield has been proposed to reduce the amount of radioactivated materials.…”

Section: Discussionmentioning

confidence: 99%

Pre‐discard estimation of radioactivated materials in positron emission tomography cyclotron systems and concrete walls of a cyclotron vault

Wagatsuma

Ishiwata

Nobuhara³

et al. 2019

Medical Physics

View full text Add to dashboard Cite

Purpose The concrete vault, cyclotron body, and peripheral equipment in a cyclotron room become radioactivated by neutrons generated by operating an unshielded cyclotron. Radionuclides and the amounts of radioactivated materials must be identified before discarding a cyclotron system. The present study aimed to reduce the amounts of concrete from cyclotron vaults, as well as cyclotron components and peripheral equipment, that will be disposed of as radioactivated waste by clarifying the nature and quantity of radioactivated materials remaining in facilities after cyclotron operations have ceased. Methods Cylindrical concrete cores were bored into all four walls, ceiling, and floor of a room where a Cypris 370 cyclotron had been operated for 22.8 yr and then cooled for 40 months. The accelerated particles comprised protons and deuterons with constant energy of 18 and 10 MeV, respectively. The types and amounts of radionuclides in these cores, in 38 components of the cyclotron including the yoke, and in 13 pieces of equipment in the room, were determined by γ‐ray spectrometry. Concentrations of radioactivity were also calculated using an updated version of Particle and Heavy Ion Transport System and DCHAIN‐SP. Amounts of materials with both measured and calculated total radioactivity concentration (ΣD) of <0.1 Bq/g were identified as being nonradioactivated. Results The major radionuclides in the concrete were 60Co and 152Eu. The radioactivated concrete was distributed to a depth of <38 cm. Most cyclotron components and equipment were radioactivated by neutrons. The major radionuclides in cyclotron components and equipment were 54Mn, 60Co, and 65Zn. A 33% volume of the yoke was regarded as nonradioactivated. Conclusions The estimated amount of radioactivated waste in the concrete was about 70,000 kg (12.5% of the total concrete). Most components of the cyclotron except for the 33% volume of the yoke (20% of the cyclotron body), as well as most peripheral equipment in the room, were radioactivated. Part‐by‐part assessments of radioactive materials using measurements and calculations could distinguish nonradioactive from radioactive materials before they are discarded.

show abstract

“…The low activation concrete, Wide-use type 1 for the fission reactor [1] is made of white Portland cement and special limestone. The concentrations of silicon, aluminum, iron, magnesium, sodium, potassium, manganese, titanium, and phosphorus of the low activation concrete are very few compared with the ordinary concrete [1] and with the geostandard sample, JA2 [2].…”

Section: Introductionmentioning

confidence: 99%

“…The concentrations of silicon, aluminum, iron, magnesium, sodium, potassium, manganese, titanium, and phosphorus of the low activation concrete are very few compared with the ordinary concrete [1] and with the geostandard sample, JA2 [2].…”

Section: Introductionmentioning

confidence: 99%

Irradiation and penetration tests of boron-doped low activation concrete using 2.45 and 14 MeV neutron sources

Morioka

Sato

Kinno

et al. 2004

Journal of Nuclear Materials

Self Cite

View full text Add to dashboard Cite

Raw Materials for Low-Activation Concrete Neutron Shields.

Cited by 10 publications

References 15 publications

Radiologic assessment of a self-shield with boron-containing water for a compact medical cyclotron

Radiologic assessment of a self-shield with boron-containing water for a compact medical cyclotron

Pre‐discard estimation of radioactivated materials in positron emission tomography cyclotron systems and concrete walls of a cyclotron vault

Irradiation and penetration tests of boron-doped low activation concrete using 2.45 and 14 MeV neutron sources

Contact Info

Product

Resources

About