What about nuclear power plants?greenspun.com : LUSENET : TimeBomb 2000 (Y2000) : One Thread
How far in terms of miles should one consider being from a nuclear power plant on 1/1/00? What is the worst case scenario for one of these plants? Will they explode? Will they emit radiation? I realize nobody knows for sure, but it seems to me it's important to consider if you live in close proximity to one or are making plans to move. Is there such a thing as a radar detection device or is there any possible way to protect yourself? Thanks and God bless. Mary
-- Mary (SWEEP6@prodigy.net), February 02, 1999
We live *very* close to one of these facilities -- so I have a vested interest in the question. First a little background:
We first addressed this question 10 years ago when we decided to buy the property. At the time, nuclear power was pretty much a dead industry - the cost of building and maintaining these facilities was simply not cost effective. No new plants were being built.
After the Three Mile Island incident, the additional safety regulations put in place had two effects (IMHO): First they added to the cost of these facilities making them even less cost-effective. Second, and more importantly, I believe they made the plants safer.
We have never been especially worried about 'meltdown' scenarios. Yes, we believe that they are possible but, relatively speaking, we believe we are much more likely to die in a traffic accident than in a containment release accident.
With respect to Y2K, we began looking at the issue again and came to the conclusion that the most likely event (other than continued operations) was a controlled shutdown, not a containment breach.
We do have three remaining concerns however:
First, if a plant is shutdown for a long period, cooling pumps must continue to operate. This requires stockpiling deisel generator fuel and spare generator parts. We do not see this as a huge issue. Yes it is serious but should be easily addressed by proper contingency planning. We believe the operators of the local facilty are treating Y2K seriously and will plan accordingly.
Second, we are concerned that, should times becomes 'especially chaotic' (TSHTF), the military will be called upon to protect the facilty as a strategic resource. If this event should occur, the first course of action the military will take is to declare an exclusion zone. The LAST thing the military will allow in an exclusion zone is a bunch of unauthorized civilians. We believe that the remote possibilty exists that our house might be inside such an exclusion zone.
Third, and most troubling, we are seeing suggestions that if these facilities cannot prove their 'readiness' by July 1 of this year, the NRC may come under political pressure to 'relax' certain safety regulations for these facilties. We would be highly opposed to any such 'relaxation' of safety regulations by the NRC. We do not consider these regulations to be 'unneccessary red tape'. These regulations are in fact a prime reason we live where we do without unnecessary fear. We would strongly oppose changing this.
After all, while should my family and my neighbors be put at higher risk because the operators of these facilities were arguably negligent in addressing their Y2K issues? We are prepared to cooperate by living without electricity for as long as it takes to get such facilities properly remediated.
If there are shortages of generating capacity, we are prepared to do without electricity so that other more critical services (hospitals, emergency services, emergency shelters, etc) can have what they need to keep functioning. We believe others should also be prepared for this contingency.
In short, though we very live close to a nuclear facility, we are not especially concerned about catastrophic containment breaches related to Y2K - at least not as the situation exists today.
-- Arnie Rimmer (email@example.com), February 02, 1999.
There was an excellent thread a couple weeks back on nuclear plants. What I never did understand from that thread was, how many days (weeks? months?) of external power is necessary to drop the temperature of the core and rods to safe levels. I gathered in general that although it can take 4 to 6 month figure for a complete shutdown, the length of time to make the plant safe is significantly shorter than that, perhaps within the range of emergency fuel storage.
I think the nuclear industry is starting to make a case that it can shut down safely. However, I also want to be far more convinced than I am that it can stay up! The public may be missing the spin that a nuclear plant that has shut down is not contributing to the grid, which in itself creates a public welfare issue (in January! here in the Northeast!). The controls sound kind of flaky, and I wonder whether a nuclear plant is far more likely to shut itself down than other utility plants.
Easy for me to say I'm not worried about a meltdown, since I'm probably at least 60 miles from the nearest source (and I have no background to speak of on this issue), but it's sounding to me more and more like a manageable situation. I predict that NRC will let at least a majority of nukes attempt to cross the rollover, which could unfortunately mean that much less of a reason for JQPublic to worry about losing power. (I'm REALLY enjoying my new wood stoves...)
Mary, let us know if you find out any more about your plant.
-- Brooks (firstname.lastname@example.org), February 02, 1999.
I've never been a "pro-nuke" person, but there is one good thing to say about them. Like Hydro plants, they don't need the continuous supply of coal/oil/gas that other plants need. If they can prove, BEYOND A DOUBT, that they can operate safely, I for one hope they stay up.
-- Sysman (email@example.com), February 02, 1999.
Three days of "forced cooldown" to get core and all other temperatures to "room temperature" is a good rule of thumb - which can be from external or internal power sources - the emergency diesels at each station (usually either 2,3, or 4 depending on system design) are designed to startup and operate completely independently of external power.
Once cooled down, there is residual heat from radioactivity in the core and spent fuel pool storage areas. Standby methods of cooling these storage areas are designed in, and there are many different ways of keeping the fuel rods covered with water - which is all that needed from a " radiation protection" standpoint.
Time frames to "add water" will depend on size of fuel pool, depth of water, initial temperature of the eater, heat loss through the concrete to the ground, outside temperature, and most important, reactor power history and amount of spent fuel present, core thermal history, exposure rates, etc.
Nuclear plant fuel or radiation exposure is not, repeat not, a Y2K-relevent problem. It is a frequent media distraction however.
-- Robert A. Cook, PE (Kennesaw, GA) (firstname.lastname@example.org), February 02, 1999.
The core temperature of a fission reactor drops quickly (within minutes) after a SCRAM. SCRAM is where the control rods (with neutron absorbers, such as boron and carbon/graphite) are dropped quickly into the core. The nuclear reaction dies very quickly in that case, in a matter of seconds. The power level drops to less than 1% of the full operating power, also. Therefore, the fuel rod temperatures remain at essentially the temperature of the cooling water (this depends on if its a pressurized (PWR) or boiling (BWR) water reactor).
If, for some reason, the cooling water disappears, then the core will begin to heat up and eventually will melt. But, there is no good reason for the water to disappear.
If the cooling water is not circulated constantly to an external heat exchanger (such as a cooling tower, lake, river, etc.), then the cooling water temperature will increase, boil, and be released as steam. Eventually, the core will heat up and melt. So, it's important to have electricity to run the main core circulation pumps. Fortunately, since the decay heat of a shutdown reactor is only about 1% of the full operating power, the coolant circulation pumps (and heat exchange system) only have to pump enough water through to cool the residual 1% decay heat power. Over a period of many months the decay heating level drops significantly below 1% and reaches a point where natural convection of the water can cool the core without any external power supply. Neat! The nuclear power plants may likely be the only power plants runningafter Y2K because they require no external fuel (only are refueled 1-2 times per year...).
-- Bob Watson, Ph.D. (email@example.com), February 02, 1999.
To continue the above notes:
Immediately after shutdown: heat rate is about 2% previous core power.
After one day, heat rate is approximately 0.5% previous core power (as noted in previous post.)
After 1 week, heat rate is approx. 0.02% previous core power, and can be considered essentially constant thereafter - though it is decreasing exponentially with a half life proportional to the remaining radioactive daughter product isotopes present after fission.
As noted, this residual heat must be removed - so lets take a worst case scenario of no power available externally (a reasonable assumption given what little we've been told about the grid) - and for some wierd reason unfathomable to me based on my experience with nuclear power plant emergency generators - there is no internal power available either.
If the core is uncovered in the reactor - as would happen in a refueling case, or if you were discussing the fuel stored in the spent fuel pool, all that is required is that water be periodically added to the pool if boiling occurs. Cooling then happens by boiling water - which at 212 degrees is far cooler than the regular operating conditions of the rods.
If the reactor were not uncovered, water would remain in the (filled) core and steam generators - and emergency cooling (without power) would occur as usual in a shutdown scenario - via the emergency injection system, spraydown system, or via natural circulation through the reactor coolant pumps and steam generator bleed.
All specifics need to reflect the actual plant design and power history - and all the above comments need to be treated in the way we are discussing the initial premise - that five redundant separate "layers" of alternative and emergency electric power systems have all failed, and none of the five alternatives can be recovered in any shape, manner, or form at all - permanently.
Also, you are completely neglecting the training and ability of the operators to re-route, rebuild, and make corrections as needed. Running a single pump and heat exchanger is not that difficult.
-- Robert A. Cook, PE (Kennesaw, GA) (firstname.lastname@example.org), February 02, 1999.
Robert and Bob - Thank you for the consise and thorough lesson in nuclear power plant operations. You're right. My only knowledge has come from the media and anti-nuclear propaganda. Mary
-- Mary (SWEEP6@prodigy.net), February 02, 1999.
The myth that 5 months is required for cooling, I believe started with Gary North making the false assumption that since fuel rods are stored in spent fuel pool storage for sometimes 5 months, cooling requires 5 months.
In support and reiteration of Robert's input (not that you aren't clear, Robert), the human factors of operator control and decision- making, based on reliable information and data, have been and will always be the more important variable in plant safety.
-- PNG (email@example.com), February 02, 1999.