Wpływ trzęsienia ziemi na reaktory w Japonii

[Ludwik Kowalski]

Dzile sie trescia komunikatu prywatnego od znznego fizyka japonskiego (12 marca, 2011)

Ludwik

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Serious rescue efforts for isolated people in destroyed

towns by tsunamis and quake are under way.

Another serious concern is of the stopped nuclear power

plants, Fukushima-I $II with 8 reactors total.

The Fukushima-I#1, 40 years old, has got the first trouble

after its automatic shut-down by the quake, which was caused

by no electricity (an emergent Diesel generator did not work

either) for driving circulation pumps of cooling water.

Consequently, decay heat of U-fuel pins could not be cooled

enough and temperature and steam pressure inside the reactor

vessel elevated continuously. Finally the melt-down of

reactor-core fuel started to happen, as detected by Cs and I

activities outside as the emergency value of reactor vessel

gas was opened to decrease the elevated steam pressure. It

happened an explosion, by mixing hydrogen-gas (generated by

H2O + high-temperature-metal interaction inside reactor) and

oxygen gas at the outside of the reactor steel-container,

which destroyed the concrete walls of the #1 plant building.

The reactor container vessel and reactor vessel were looked

not damaged.

TEPCO (Tokyo Electric Power Corp.) and NISA (Nuclear and

Industrial Safety Agency) decided to fill the inside and

out-side of reactor vessel with sea-water adding borated

acid to cool the reactor. The work was done. Radioactivity

monitors outside showed decrease of radiation level to about

ten times of natural BG, which was about several 100 times

just after the emergency gas-valve opening. Now the reactor

is confined stable. Citizens inside 20 km radius were

evacuated for safety.

(I think, the usage of sea water, emergent use, was chosen

by two reasons: 1) not enough pure-water was not available

at the site, 2) NaCl contained in sea water, as well as

added borated acid (B-10) has significant thermal-neutron

absorption effect which may help avoiding a worst

criticality accident of fallen debris of melt U-fuels into

water pool of container vessel, if happened.)

Probably the Fukushima-I#1 reactor will be closed

(disassembled) in near future. But we still need careful

watching what will be going on.

Now it is aired that Fukushima-I#3 reactor has got a similar

trouble. They might do similar treatment, not decided yet.

[Ludwik Kowalski]

Stan zburzonych reaktorow Japonskich

Skonczyl sie juz stan awaryjny reactorow w Fukushima. Nastepny stan (“decommisioning” po angielsku) potrwa jeszcze 40 lat.

http://tinyurl.com/8yshwhy

Ludwik Kowalski (zobacz Wikipedia)

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