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JAEA Reports

The estimation of the amount of radioactive waste from decommissioning of the nuclear facilities in O-arai Engineering Center

Tanimoto, Kenichi; Aihara, Nagafumi; ; ; ; ;

JNC TN9410 99-002, 320 Pages, 1998/11

The estimation of the amount of radioactive waste produced from nuclear facilities in O-arai Engineering Center was performed for the purpose of using it for countermeasure of decommissioning planning. The conditions and the result of the estimation are as follows; (1)The total amount of occurrence of radioactive waste is 18,820tons. As the items of the amount in radioactive level, the amount of 1GBq/t and over is 820 tons and that of under 1GBq/t is 18,000 tons. (2)The amount of metal waste is 5,820 tons and the amount of concrete is 13,000 tons. (3)Above calculation was based on related specifications, complete drawings, and visual observation. (4)To dismantle facilities, it must exfoliate the surface of wall. As for the polluted zone and the zone with possibility of pollution, it decided to exfoliate 5 cm in thickness from the surface of the wall. And, as for the zone that fundamentally pollution was not there, it decided to exfoliate surface 1cm in thickness from the surface of the wall. (5)Using the suitable decontamination technology and exfoliation technology can reduce the amount of radioactive waste. (6)In the facilities dealing with sealed source judging from the past record of operation, there is no contact with the radioactive material, etc. Therefore, it can be disposed of all the waste that comes out from the facilities as non-radioactive waste.

JAEA Reports

None

; Nagai, Akinori; ; ;

PNC TN9440 97-014, 27 Pages, 1997/08

PNC-TN9440-97-014.pdf:1.43MB

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JAEA Reports

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; Nagai, Akinori; ; *; ;

PNC TN9440 96-021, 51 Pages, 1996/08

PNC-TN9440-96-021.pdf:1.33MB

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JAEA Reports

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; Nagai, Akinori; ; ;

PNC TN9440 96-009, 102 Pages, 1996/04

PNC-TN9440-96-009.pdf:3.18MB

None

JAEA Reports

Operation experience report of experimental fast reactor JOYO; A special level monitoring for reactor vessel in the occurrance of the abnormal 1evel incident

; ; ; ; Ozawa, Kenji; ; Terunuma, Seiichi

PNC TN9410 91-187, 41 Pages, 1991/07

PNC-TN9410-91-187.pdf:1.0MB

A reactor vessel in JOYO provides three induction type level meters which is defined in the safety protection system. They have two kinds of measuring range and display the sodium level below to the discharge nozzle of the primary cooling system. One is from 350mm about the normal sodium level to 1,600mm below it and other two sets are from 350mm above to 350mm below it. This report describes a special monitoring method of sodium level in the occurrence of the abnormal sodium level incident which reaches it more than 1600㎜ below the normal sodium level in the reactor vessel. The special monitoring method uses the discharge sodium pressure of the primary auxiliary cooling pump. A discharge sodium pipe from the primary auxiliary cooling pump is located in the bottom of the reactor vessel and it's discharge pressure is correlated with the reactor vessel sodium level which works back pressure to the pump. Therefore, it was assumed that abnormal sodium level which reaches it more than 1600mm below the normal sodium level can be monitored using this discharge sodium pressure. A verification test was conducted to measure the correlation of the discharge sodium pressure and the reactor vessel sodium level. Main results obtained from this test were as follows. (1)Validity of this special level monitoring method was confirmed in the sodium level range from normal to 3,390㎜ below it and in case of sodium level changing which is decreased at the rate of 47.5m $^{3}$ /h by this test during the system sodium drain work. (2)A correlation equation is obtained using parameters of discharge sodium pressure, flow and temperature of the primary auxiliary cooling system to gain sodium level of reactor vessel. (3)Parametor chart of the reactor vessel sodium level was made using multi regressive analysis.

JAEA Reports

Purity control results of coolant sodium and argon gas in JOYO data conections of purity control (19751987)

*; *; ; *; *; *; *

PNC TN9450 88-005, 136 Pages, 1988/05

PNC-TN9450-88-005.pdf:3.25MB

This paper is the impurities eontrol experience data collections in primary and secondary sodium and argon gas for the purpose of build up data base, from the initial sodium fill of the system in 1975 to the 100 MW cycle operation in 1987 in JOYO. Main results of the impurities monitoring in this period were as follows. (1)Impurities concentrations in primary and secondary sodium were generally within the control level of JOYO. (2)Although hydrogen and methane concentrations in primary argon gas exceeded the control level during maintenance of primary system main circulating pump and fuel handling works, other items were well controlled within the level. (3)Impurities concentrations in secondary argon gas were generally within the control level, except hydrogen concentration at the 6th periodical inspection and maintenance in 1987.

JAEA Reports

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*; *; ; *; *; *; *

PNC TN9410 88-183, 61 Pages, 1988/01

PNC-TN9410-88-183.pdf:4.04MB

None

JAEA Reports

Report of operation experience on JOYO purity monitoring of coolant sodium and cover gas in the period from MK-II core conversion work to 100MW 7th cycle

*; *; *; *; *; *

PNC TN9410 87-174, 128 Pages, 1987/12

PNC-TN9410-87-174.pdf:8.49MB

Monitoring of impurities concentration and radioactivity in coolant sodium and cover gas argon has been continued for the purpose of purity control on JOYO. This report deals with the results of these monitoring during 1983 to 1985. Typical characteristics are followed. (1)Impurities concentrations in primary and secondary sodium were generally within the reference limits of JOYO. (2)Although hydrogen and methane concentrations in primary cover gas argon exceeded the reference limits during maintenance of primary system main circulating pump and fuel handling works, other items were well controlled within the limits. Particularly nitrogen concentrations in primary cover gas argon decreased to 1/5 as MK-I Core. This is due to vanishment of undifined air leak-in during the MK-I Core operation and diclution effect of blow down for fuel handling charge machine during core conversion works. (3)When vent type control rods were newly inserted to the reactor core, initially in helium gas in the rods were released to the primary cover gas during irradiation core conversion period. Tts concentrations were 734ppm. And helium concentrations produced by neutron reaction in the control rod absorber were decreased as withdrawal of control rods. (4)Impurity concentrations in secondary cover gas argon were generally within the reference limits of JOYO. (5)Radioactive corrosion products deposited in the primary sodium sampler were gradually increased with reactor opration time elapsed. And, dose rate at the surface of sampler was less than 10 mR/h after $^{24}$ Na decay.