"Long Night" over we move onto lighter content.
|The Chernobyl Power Complex (130 km north of Kiev, Ukraine) overlooking an artificial lake ( 22 km2 ) and situated beside the river Pripyat|
The Chernobyl mini-series.
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, rods and 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 in a mood. I later learn he had signed papers stating the test had been done 2 year prior during initial start up phase when in fact it had not.
There are 4 units reactor units, apparently all cross wired on busbars 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 water that entered 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, electricians as well. One of the senior engineers job to look at the oscilloscope and observe waveforms during the test. The fateful test had been attempted 3 times earlier during the 1980's all unsuccessful. Despite apparently being self-powered the feeling that the event of a total grid dropout wanted some way of running circulating pumps without "leaving the building". What voltage the circulating pumps ran on perhaps something like 550 VAC 3 phase. The picture does not show coils going into the pump (it may not be practical to operate any higher) During the test the generator is spun-up, then steam to it turned off then the free wheeling spinning generator with decaying 20 KV signal switched into the circulating pumps?!?
A heavy mismatch at best.. Standing wave? Certainly. Dangerous? Yes. Damaging to attached equipment? Very possible. Void any sense of warantee? If you did that to my piece of equipment? yes.
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.
Short List of references: