But there is also one more, "the most important violation of regulations", which stick out less to general public , but in conversations with experts it is the core, as though it has blown up the reactor. This violation consists in reactor work at small operating reactivity margin (ORM) that the regulations strictly forbid.
- Really, forbids? Why? Is it possible because the reactor thus can blow up? Then why in regulations about it is told nothing? If this parameter so is important, that the operator should it vigilantly to watch, on what measuring device he should do it?
- What did you say? Such device does not exist? Really?! And how then you have learnt, that during that moment was small ORM?
- On a result listing of phys.-calculation, made from a magnetic tape of the computer complex already after accident.
I do not know as at you, the reader, but at me a feeling of a madhouse arises from such dialogue. Besides that on us palm off as operative parameter some data not measured directly and which obtaining demands not less than 5 minutes of time. Thus some more there keep us as idiots.
Yes, in regulations there are restrictions on value of ORM, but let's look how it is written down there. Also we will compare to that how restrictions for other parameters important for safety are written down. (see ”The Regulations and ORM"). This analysis shows that, despite the presence in one point of regulations the terrible requirement to shut down immediately the reactor at decrease ORM to 15 rods, ORM is not considered as parameter important for safety. Its value is fixed by economic reasons, but not of safety reasons.
Shoot me if record in regulations on ORM restriction can be read somehow differently than below-mentioned mode.
At work at constant (nominal) power level the reactivity margin from uranium burning out decreases approximately for 1/2 [RR] rods a day. Do not keep up this reduction to ORM=26-30 rods. (do overloads in due time). This limit can be lowered by the permission of the CEP (chief engineer of the plant), but no more than to 15 rods. If you cannot sustain these requirements, shut down the reactor (and get your deserts for it).
In case of sudden shut down or a great power drop and fall into the hole of “poison out time” is allowed to restart the reactor (right after elimination of the failure causes), only having a sufficient reactivity margin, so that on exit to have ORM not below 15 rods. If too long dawdled also the reactor has had time to poison strongly then shut down and wait while the poison out time will pass.
As we see, following these requirements of regulations (regarding reactor shut down) can threaten with a scolding from the heads, and what is the threat from its violation? No threat, only thanks. The has less reactivity margin you will keep up in a steady state operation mode, the fuel burning out in unloaded HGA will be deeper and the operate of NPP will be more economic.
If you can thus pull out somehow the power from a downfall, even if at a zero reactivity margin, will be idle times less, and besides it will be increase of an overall performance of the NPP.br>
So, as it is sung in a song "think, solve, to have or not to have". But the words would be absolutely another if the matter concerned safety, especially nuclear safety.
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