User talk:Sredmash

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Welcome![edit]

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Happy editing! HopsonRoad (talk) 00:56, 16 September 2021 (UTC)[reply]

Chernobyl[edit]

Howdy. While I appreciate your work on Chernobyl, you've changed some factual items without citing to a reliable source. Could you either cite to the sources you've used or otherwise list them on Chernobyl's talk page so they can be incorporated? Thanks. CaptainEek Edits Ho Cap'n! 16:27, 20 September 2021 (UTC)[reply]

I have an ongoing Talk Page section about it, and sources are in progress. Feel free to call out any of the specific edits, since there are several.Sredmash (talk) 19:19, 20 September 2021 (UTC)[reply]

Cause of initial power drop at ChNPP 1986[edit]

If the operators' failure to account for neutron absorption (by decreasing reactor power too quickly) was not the cause, what was? KnowledgeableHrvatica (talk) 02:31, 14 July 2022 (UTC)[reply]

They weren't decreasing power too quickly, nor could they somehow fail to account for xenon poisoning, which would be akin to an airline pilot forgetting about gravity. The proximate cause of the power drop was AR-2 failing to enter operation due to an imbalance in its sensor chambers, leading to a loss of control over the reactor. Most likely there were some perturbations in the feedwater as well, which in a reactor with a strong positive void coefficient has the potential to rapidly affect reactivity. Control over feedwater is very difficult at low power levels. Most sources attribute the drop to human error, but if so it was a control failure and not related to awareness of xenon poisoning. Neutron absorption served as the necessary conditions for the drop and likely perpetuated it, but the trigger lay elsewhere. At 0:30 the amount of xenon poisoning was actually substantially LESS than would have been the case if not for the unplanned delay in the test.Sredmash (talk) 12:30, 14 July 2022 (UTC)[reply]
You are correct that the automatic regulators failed (and was a major contributor to the accident), but my understanding is that they had failed to decrease reactor power and for this reason the power decrease was not made by the automatic regulators but instead by the operator using the power reduction controls.
Sometimes, due to sudden increased workload (such as in this incident), a pilot can make errors similar to "forgetting about gravity", be it erroneous autopilot inputs or forgetting flap configurations. Countless times in aviation history there have been events where pilots simply "forget" airspeed is required for lift and crash their aircraft. Perhaps the reactor power reduction button needed a vibrating stall warning lol. KnowledgeableHrvatica (talk) 10:06, 15 July 2022 (UTC)[reply]
The power reduction seems to have been partially deliberate in order to remove the imbalance in the AR sensor chamber and regain control. Most sources assume there was an error, just not one related to xenon per se. Dyatlov wrote that it was very common to experience power drops of various magnitudes while switching from one regulator to another, and Tregub regarded the drop as a normal occurrence which was easy enough to correct. By analogy your flaps jamming for a few moments is a big problem when flying at low altitude and airspeed, but altitude and airspeed is just the context of the failure rather than its cause.Sredmash (talk) 12:33, 15 July 2022 (UTC)[reply]
Well in my analogy, the cause was meant to be the pilot inducing a stall and forgetting how to recover.
Also, I don't exactly why everyone (including the IAEA people) seems to think that manual power drop was meant to somehow fix the (I assume) miscalibrated ionization sensor. To me, it just looks like they acknowledged the miscalibration and simply "manually" controlled the reactor instead of relying on quantitative inputs into an apparently unreliable AR. KnowledgeableHrvatica (talk) 16:03, 15 July 2022 (UTC)[reply]

IAEA "4000-9000 additional fatalities from potential increases in cancer mortality"[edit]

I figured discussing here would be better than cluttering the history page. I have some points to make:

Firstly, the source for this number is the IAEA report. This is the only source of this information, and all other instances are simply citing this report. This will also provide much necessary background info.

Secondly, the "up to 4000" is in reference to the ~600,000 rescue workers, not the millions who reside in the contaminated zone. The estimate for them is ~9000.

Thirdly simply because lots of people have cited something does not mean it is meaningful or reliable. In this case, it is not very meaningful. Aside from impacting treatment (such as the psychosomatic effects I just added to the page), there is no radiation effect (at least that I am aware of) which increases cancer mortality without a corresponding increase in incidence rate. This was apparently not made very clear in the report and is entirely omitted in nearly every source which cites this. If there is no increase in incidence rate, there cannot be an increase in mortality rate from radiation effects. The only exception to this that I can think of is if the mortality rate increases to become statistically detectable without a detectable increase in incidence (i.e. the incidence of ultra-lethal cancers), but such the number of new mortalities would be very small. The meaning behind this speculative ~4000/9000 number is to state the possible maximum externalities of a delayed increase in cancer incidence (which they also explicitly mention). However, not only has no increase in cancer incidence been found (aside from childhood thyroid cancer), this report was made 17 years ago and future maximums would be significantly smaller,. This estimate of ~4000/9000 was weakly relevant in 2005 and barely relevant now. The report explicitly warns about the usefulness of this projection, but journalists will always pick the larger numbers. There is a good reason why they did not include estimates of increased mortality rates from psychosomatic effects.

I could also rant about the harmful minimizing/maximizing effects of such an estimate becoming so high-profile, but I will save the effort. Unless I am possibly misunderstanding a concept, I can either include this explanation in the already-too-long summary section, or this could simply be included in a later section and removed from the summary.

KnowledgeableHrvatica (talk) 16:39, 15 July 2022 (UTC)[reply]

You may be overlooking the fact that 4000 deaths or even 9000 deaths would be completely invisible in these particular populations. The corresponding cancer incidence would likewise be lost in the statistical noise, meaning that the lack of evidence is not evidence of absence when the projections line up with observed results from the LSS, etc. (There is however an emerging consensus regarding a small increase in leukemia and cardiovascular problems among former liquidators.) But let's just be frank here. I know you are approaching this from a pro-nuclear perspective (as am I), and in this context the 4000 number is a god-send. You will never get anyone to pay attention to a lower one, and it is the best antidote to the Greenpeace estimates that will wind up in this articles one day otherwise. That said, if you are interested in my personal opinion, estimating liquidator mortality based on the average dose of around 150 mSv is also a flawed exercise because it does not address the several thousand outliers who systematically exceeded their 250 mSv dose limits, sometimes by more than 100%. Of course the data do not exist with regards to the overexposed, making this a job for historians when assessing the mountain of anecdotal evidence. When just about every higher-ranking engineer or specialist talks about hiding their dosimeter in their memoirs, it adds up to something.Sredmash (talk) 22:36, 15 July 2022 (UTC)[reply]

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