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The Chernobyl mini-series.
|The Chernobyl Power Complex (130 km north of Kiev, Ukraine) overlooking an artificial lake ( 22 km2 ) and situated beside the river Pripyat|
What I became interested in was the lack of detailing of the electrical end of what they were trying to accomplish. Attempting to comprehend the vast complex of plumbing and rods in an immense electrical generating station.
The nature of the test they did not delve into.. Contradictory reports amidst cover-up and lost details. The mini-series depicts the director at the control room and in a mood. I later learn he had signed papers stating said test had been done 2 year prior during initial start up phase when in fact it had not.
The Test involves disconnecting the turbines from steam and relay connecting them to the system's water pumps. The theory is that while the spinning down turbines produce a decaying signal, they can power the critical water pumps during the switchover to generators. (from experience this is typically 2-3 minutes)
The Facility There are 4 units reactor units, apparently all cross wired on bus-bars to power their own station vs. the assumption the plant ran off the street. Started work in the 1970's the first two units' buildings are of an earlier generation than units 3 and 4. Construction on units 5 and 6 was halted a few years after the unit 4 accident.
The machine refers (in one explanation) to the design as it becomes unstable below 20% thermal output. (Max 3,000 MW) High temperature mitigates the positive void effect. This type of reactor is a light water boiler. The same water that enters the chamber produces the steam that powers the 2 500 MW (electrical) generators. No heat exchanger. A machine raises and lowers fuel bundles so the reactor could continue operation while being refueled.
Electrical There were electrical engineers on 3rd shift duty and electricians as well. One of the senior engineers job to look at the oscilloscope and observe wave forms during the test. The fateful test had been attempted 3 times earlier during the 1980's all unsuccessful. Despite the plant being self-powered the feeling that in the event of a grid dropout they wanted some way of running circulating pumps. These pumps ran on something like 550 VAC 3 phase. The picture does not show coils going into the pump and my feeling is that any motor with a winding cannot operate at any higher voltage. During the test the turbine steam is cut off then the decaying 20 KV signal switched into the circulating pumps.
A serious signal mismatch at best.
Layout There is a reactor hall, which there is a video on, there is a mechanical hall housing turbines attached to 20KV, 50 Hz electrical generators. This power winds up after transformers at 750 KV on it's way to consumers. There is an aerator and de-aerator gallery that separates waster from steam. A vast complex with access and plumbing above and below the reactor core which itself has an upper and lower biological shield.
Other incidents 1991 about 10 weeks before the December meltdown of the Soviet Union, Reactor 3's mechanical room had a generator faulty switch fire ignites the shaft lubricating hydrogen which melts a roof support causing the partial collapse of the roof above the mechanical hall. Reactor 3 was shut down. Gorbachev cited Chernobyl as possibly the reason the Soviet Union collapsed. In early 1980's one of the units had a partial meltdown. Later versions of the RBMK design utilized more control rods as well as higher level (better grade) of enriched (1.8 to 2.0 then ultimately at 2.4 percent) Uranium mitigating the value of the steam-void coefficient.
Nuclear History Videos and lists going back to the 1950's show the development of procedures based on mistakes, fatalities and release of radiation in other countries including United States, Canada and Europe. Soviets just did it better. The Khyztem disaster of the 1950's and associated cover-up the subject of videos and at least one documentary going back some time.
For Chernobyl a list of 60 ish names of plant personnel who were on site including one from the previous shift who took fatal doses. Some died within hours. One body (Valery I. Khodemchuk) was never recovered. The other plants continued to run some years. About 10 RBMK reactors are still running, RBMK refers to the names of the reactor development.
Some feeling during the reading of information provides some in-between the lines feeling for the cultural difference between the design and science and what should have been done as opposed to Soviet cost and corner cutting to meet or rush policy driven production goals.
New Safe Confinement Shelter is rolled into place in 2016. The largest structure ever made that moved into position on rollers. A mammoth undertaking designed to last 100 years without relying on the existing structure.
2022 Update The remaining 3 reactors now closed down but are still staffed and guarded by 169 reservists. Some state of power and cooling must be maintained to the remaining fuel in the now inoperative reactors. With the recent Russian invasion of Ukraine they decide the facility is a target and engage the guards in what is shaping up to be called the "Battle of Chernobyl" Their equipment, tanks and armored vehicles kick up radioactive dust in and around the "red forest" Further they dug and dwelled in trenches in the forest exposing themselves to higher levels of radiation. Apparently on their way out some stole some highly radioactive "souvenirs" causing the much higher doses reported in the news.
The Red Forest After the disaster a 4 square mile forest was killed by the radiation, bulldozed dumped in trenches and buried with sand. Vegetation and wildlife have returned to the forest yet it is still contaminated with high levels of strontium-90 and caesium-137.
During the Visit the power was cut to the facility for three days. On purpose? speaks to a gross negligence. During the visit the engineer on site speaks of trying to reason with the soldiers (who were asking many questions oh how to run a nuclear facility) and having to scramble for fuel to keep the generator (that keeps the remaining cores stable) running. What would have happened if the generator failed? Idiots When engaging a nuclear power plant as a military target, bring along someone who know what they are doing and that you have to answer to!
The Russian return to where the Soviet collapse all started seems apropos in order to draw western military high technology into the region and get the U.S. involved in what seems increasingly a civil war between Russian states. The Chernobyl visit punctuates that among the "highly educated" workers that emigrated from Russia in February 2022 their nuclear people went with.
Short List of references:
The new containment dome.