there are a number of questions that need answer regarding the situation at the Fukushima Daiichi nuclear reactor, aka Fuk-D.
As a starting point, here is an amateur online feed of radiation in Tokyo (Park18).
It is a geiger-counter, the normal count rate is 10-20 cpm, around noon on march 15th the count rate peaked at about 120 cpm, the counts then dropped before there was another broad rise on march 16th to about 40 cpm.
The first question is: why am I having to link to an amateur with a geiger counter?
The Japanese Atomic Energy Authority has four online environmental radiation monitors.
All went offline at 4 pm on friday march 11th and have not come back.
I understand they are busy, I understand that they don’t want to panic people, but this is stupid.
I don’t have the energy to get into the weaknesses of 40 year old GE designs for the Mark I Boiling Water Reactor.
BWR containment specs and age related safety management (pdf) – IAEA TECDOC-1181 has many of the gory details if you care – including descriptions of the generic containment layers.
Nuclear power has its place, I accept that Tokyo Electric Power Company might have reasonably spec’d magnitude 8 as a reasonable maximum earthquake to design for, and who knew a tsunami (in Japan of all places!) would wipe out all the backups, and that it was bad luck the 9th magnitude quake hit just before the oldest reactor was scheduled to be shut down (modulo the decade extension for pure profit operation).
So, riddle me this:
- The reactors are supposed to scram when alerted to a major earthquake.
Given the location, Fuk-D had about 30 seconds to scram.
A Mark I BWR should be able to insert the control rods in 10 seconds.
Was it automatic? Require manual override decision?
The design has control rods go up into the core, not drop in. Did they go all the way in before the whole thing jumped? Or did they buckle?
I’m sure the operators have been debriefed and there is an incidence officer who knows the timeline for the first couple of days.
- What has been emitted?
It is known, even if the PR department has not been briefed, and journalists couldn’t tell us when it is spelled out for them.
Radiation need proper units when reported: we need milliSieverts per unit time, total curies, date stamps and size of contaminated area.
As y’all know, ambient dosage is about a milliSievert per year.
Occupational limit doses are usually 20 milliSieverts or so for a year.
So background is about 0.1 microSivert per hour (or One Banana Equivalent Dose – man that 40K is nasty).
An acute dosage of a Sievert puts you in hospital.
10 Sieverts and you are not coming out of hospital.
So, if there are measurements of 400 milliSieverts per hour at the site, as was reported on the 15th, workers who volunteer can only last about an hour before having to leave, permanently.
But, is that a single small spot due to direct exposure to fuel elements? Or a little burp of 16N – with half-life of 7 secs it is hot, but not for long?
How big is the spot that is, or was, so hot?
- What isotopes are being measured on site?
Are they seeing 137Cs and 131I?
Technetium? In what quantities.
Are the fuel rods compromised and venting?
Is the containment leaking?
You can “detect” anomalous radioisotopes in extremely low concentrations, what matters is how much material is dispersed and in what form.
Basic question: did the scram of any of the reactor cores fail, and are there therefore any of the reactors sitting there with critical sub-cores – chunks of uranium still undergoing sustained fission?
If not, did the loss of primary coolant occur early enough for substantial breach of fuel rods due to thermal stress, and has the resultant fuel dispersal lead to undesigned criticality?
Are the random blobs that fell out sitting there undergoing nuclear reactions.
TEPCO ought to know this by now, and it makes a very big difference whether these are just hot cores sputtering while residual heat is bled away, or whether they are undergoing fission without permission of the operators and without actual functioning cooling systems, or containment…
Hot damaged cores are bad.
Unscheduled fission in cores is catastrophic.
Oh, and please, someone, explain to journalists that “white smoke” is often the thing popularly known as “steam”.
Go to MIT NSE Nuclear Information Hub for actual authoritative information
PS: General Electric website with fact sheets and news – eg GE is shipping new mobile generators to Fukushima, say they offered, took TEPCO this long to take them up on it.