Jeffrey LewisHayden Sticks to Al Kibar Size Estimate

CIA Director General Michael Hayden stuck to the size estimate of the Al Kibar yesterday, comparing it to Yongbyon:

“In the course of a year after they got full up, they would have produced enough plutonium for one or two weapons,” Hayden told reporters after a speech.

The reactor was of a “similar size and technology” to North Korea’s Yongbyon reactor, Hayden said, disputing speculation it was smaller than the Korean facility.

“We would estimate that the production rate there would be about the same as Yongbyon, which is about enough plutonium for one or two weapons per year,” he said.

(via Total Wonkerr)

The CIA estimates that Yongbyon produces “about 6 kg per year” of plutonium. (I think it is a stretch to call that one “or two” weapons per year but whatever.)

So, the IC must really think it is the same size.

A couple of summary points about the How Big Was Al Kibar post:

  • The ratio of entry points for the fuel and control rods is 61:97. Extrapolating capacity from the number of entry points is not straightforward, but capacity if the entry points imply a proportional number of fuel and control rods, the reactor could be significantly smaller than Yongbyon.
  • On the other hand, the core could still be the same size, of course, just with fewer entry points. I took a quick look at the collapsed concrete containment vessel and came up with like 10 meters — a little tight for a Yongbyon-sized pressure vessel (884 centimeters), but not clearly impossible. That estimate could easily be off by 1 or 2 meters.

This is all very interesting. Thoughts?

Comments

  1. Yossi, Jerusalem

    English Magnox reactors have fuel channel lattice pitch of 20cm give or take 1.5%. Yongbyon seems to have similar pitch, probably 20.3cm like Calder Hall. The Yongbyon distance between two “access ports” seems to be 60.9cm (or a few millimeters less). These calculations are not difficult and I can perform them in detail if asked.

    I think NK doesn’t aspire to innovate on Magnox technology but warm and feed its children by NOT producing Plutonium on its own land. If it built a reactor for Syria it wouldn’t risk changing designs. We can assume the inter port distance of a NK/Syrian Magnox (if it existed) to be about 60.9cm.

    If the CIA reactor has at most 8 access ports in a row we should expect the core diameter to be about (8+1)*0.609 = 5.48m. If there are rows of 10 ports, diameter will be (10+1)*0.609 = 6.7m. Yongbyon is 6.43m so it seems the CIA reactor has a similar diameter.

    When estimating the dimensions of the pressure vessel we may assume the photo was taken at man eye height (the photo is nicely composed) and look for rebar rows which diverge upwards and downwards. If we are lucky we will find between them a rebar row that seems horizontal and therefore is at eye height. I think the 4th row is more or less horizontal and assuming 1.60m for eye height we get that each row is 0.4m. It seems the mid-section is about 0.4*14 = 5.6m.

    The end-section height can be estimated in several ways. Rwendled thinks it’s 2.5m assuming the hole is 0.5m. The height seems to be about third of the diameter which may be assumed to be about 6-7m so this method gives 2-2.3m. Another method could be to count rebar rows and extrapolate at the top, it seems this method gives similar results.

    Assuming one mid-section we get 2.2+5.6+2.2 = 10m for the pressure vessel height. This is much shorter than Yongbyon. If there are two mid-sections the height is 15.6 which is still about 1m less than Yongbyon. The chief US disinformation officer says the CIA reactor could produce Plutonium at a rate like Yongbyon so maybe he has photos showing two mid-sections.

  2. FSB

    Well, Bush at least out-and-out said this was (partly) a warning to Iran .

    Great, so it is now OK to illegally attack country A to send a message to country B. Sheesh.

    Returning to a topic I & “Blowback” raised from the previous post on this: is there any way to confirm that any of the photos of the interior, are really of the interior of the BoE? (Or, ex-BoE, I should say).

    Besides the word of Israeli Intelligence?

    Though in the briefing Intelligence officer 2 (“Duece”) says they managed to piece together a confirmation, this jig-saw puzzle was handed to US Intelligence from Israeli Intelligence to solve. Clearly, Israeli Intelligence can concoct a series of photos so that US Intelligence arrives at the Israeli’s desired conclusion.

    For some reason I do not 100% trust the Israeli Intelligence.

  3. Yossi, Jerusalem

    There is something strange with my core diameter calculation. It looks like a proof that 97 equals some smaller number. Maybe I managed to reconstruct the mistake made by the CIA?

  4. Yossi, Jerusalem

    Maybe I found the problem with my core diameter calculation. I arbitrarily added one lattice cell so no fuel rod would be too close to the core edge. Without this artificial addition the diameter will be in the range 0.609*8=4.87 to 0.609*10=6.09, both smaller than Yongbyon’s 6.43m.

  5. James (History)

    Why innovate? Now I’m scratching my head over their persistence in maintaining this was “of similar size and technology as Yongbyon.” If it’s of similar size, it’s of different design. If the design is similar, then it’s clearly smaller.

    Perhaps in their eagerness to condemn both North Korea and Syria at the same time, they are compelled to deny this. After all, if it is much smaller, it’s not a very good plant for a weapons program. It would take at least two years of full-scale production to produce a single bomb. On the other hand, if it’s the same size, then North Korea is plausibly innocent of the charge of exporting weapons technology because the reactor is no more similar to Yongbyon than it is to Calder Hall.

    This makes me wonder if the timing of the release really is much more about North Korea than Syria. Everyone seems ready to accept the fact that the interior photos are genuine but nothing they released really demonstrates North Korean involvement. We are back to the question: does Syria really need the help of a nation that’s even more isolated and backwards than Syria to help them replicate Calder Hall?

  6. FSB

    James,
    not everyone accepts that the photos are of the interior of the BoE.

    Also, in Sid Hersch’s article he mentions cell phone interceptions of Koreans. Or people talking Korean.

    This (BoE) could have been a Scud related building as Cirincione had said some time back.

    Why don’t US Intel. release the rest of the photos that allegedly link the reactor-to-perhaps-be with the outside of the BoE? However, even if this is done, we do not know whether or not this trail of photos may have been concocted by Israeli Intelligence to mislead US Intelligence.

    I would also like to see someone show where they think the tarp-covered regions (shown at ground level) may have been in any epoch of the overhead shots?

    Lastly, the timing may be about Iran. See my post re. Bush above.

  7. abcd (History)

    “(Or, ex-BoE, I should say).”

    We could simplify matters and resort to calling it from here on out…Xbox. :)

  8. Yale Simkin (History)

    Yossi,
    I lean to the likelihood that the LEGO Factory reactor does have another ring of “sonotubes” ready to install.

    This would give it a 10 tube diameter (and 76 tube grid – ignoring the tubes like the centerline three.)

    Inasmuch as the row just to the right-of-center does have 10 tubes, we know they fit. (Anything that exists is possible.) Plus piles of unused tubes surround the area.

    With the 10 tube diameter, you calculated 6.09 meters for the LEGO versus 6.43 meters for the NK core.

    That is a difference of only 34 cm, or the length of a basketball player’s shoe.

    This difference is less than the inherent fuzziness of the estimates and assumptions used in the calculations.

    I would say that within the estimate’s precision, with the 10 tube option, the NK and LEGO cores have the same diameter.

    I am re-posting these images again because it makes it easier to describe.

  9. Yossi, Jerusalem

    Correcting the core diameter will affect my calculation of the pressure vessel (PV) height.

    I made another mistake: assuming the PV diameter is like the core diameter when it’s about 1.4 times larger.

    Correcting both mistakes will make the PV height (assuming two mid-sections) either:

    2*2.2 + 2*5.6 = 15.6m or
    2*2.8 + 2*5.6 = 16.8m

    Note that Yongbyon is 16.8m long so the same fuel rods would probably fit!

  10. Jeffrey Lewis (History)

    Yale:

    The thing I don’t get is that the IC diagram shows the 4-6-8 construction for a total of 61 entry ports. 52+9.

    How do you assess that?

  11. Andy (History)

    What does “similar size” mean exactly when referring to nuclear reactors? ISTM it could mean a bunch of different things depending on context and the main context is plutonium production capacity, though it doesn’t seem like that is what he’s referring to.

    Anyway, I think a key question is how that reactor could achieve Hayden’s stated pu-production capability based on what we know – a smaller number of access ports, a magnox design and a containment vessel less than 10m in diameter. What core design with those known variables would produce ~6kg pu a year at peak efficiency?

    I think Yale makes a good argument – what are those spare tubes for if not additional ports?

    FSB,

    While skepticism is always a good thing I would not expect to see any “proof” the interior photos are “real” anytime soon. How is it possible to prove they aren’t fakes in any event? One could just as easily say everything is faked, including the outside pictures.

    As was mentioned before, the photos we have are only a handful of those the IC has in its possession and Jeffrey has already pointed to the some of the methodologies the IC used to verify them. There are also the post-strike satellite pictures, which clearly show the reactor hall as well as the containment vessel. For Israel to have faked these, they would have to have intimate knowledge of this Syrian facility to include knowledge of the size and location of the buried containment vessel as well as the duct routing and all the little details that intel people look at. Israel would also have to know the US didn’t have any intelligence that would directly refute the conclusion these pictures point to. Additionally, Israel would have to know that post-strike intelligence would only confirm what these pictures imply. That is only the tip of the iceberg on what Israel would have to do or know in order to pull off what you are alleging. Besides, even without the interior pictures, there’s still substantial circumstantial evidence pointing to a reactor. It’s quite the coincidence that the “scud” or whatever facility Israel wanted to bomb just happens to be so consistent with a covert nuclear reactor that the “fake” interior pictures are nicely buttressed by the circumstantial evidence. So yes, it’s possible the interior photos were faked, but it is quite improbable, to put it charitably.

    I also think you assume the US simply takes intelligence provided by other nations at face value. That is definitely not the case, particularly with intelligence like this with far-reaching implications.

    And to what purpose such fakery? Israel already blew the place up, not the US. What is served by “conning” the US into believing the site was a reactor as opposed to something more mundane?

    All this is not imply that we should drink the kool-aid – healthy skepticism is always a good thing but so far there is nothing to indicate or otherwise suggest the pictures are fake.

    Oh, and BTW, your claim of the strike’s “illegality” that you keep mentioning is substantially lessened by the fact that Syria and Israel are in a de jure state of war and have been longer than I’ve been alive. Had this been Egypt or Jordan, then you’d have an argument.

  12. Yossi, Jerusalem

    Yale thanks, it’s a pleasure to work with you!

    I do all the calculations in parallel for 8 and 10 maximal row of access ports. You are right that the 10 port version is getting to be suspiciously like Yongbyon itself.

    I see in the Sandia report on Yongbyon the term “effective core diameter”. This probably means there are at least two meaningful measures of the diameter and being ignorant of the difference I’m introducing some error.

    Maybe we are seeing old photos from Yongbyon construction sold to Israel by some Nork claiming they were taken in Syria to raise the price? The way the CIA tied them to the overhead photos sounds great but in practice may be just self deception. The eye level method for calculating the PV height argues against it because Norks are supposed to be underfed and short ;->

    I guess the photo trail from the crawl space to the window argues for a spy instructed to supply a tie between the two kinds of photos types even if some photos show non-interesting detail.

    Until tomorrow I have a very limited graphics capabilities.

  13. Rwendland (History)

    Yale, I doubt that there is another ring of “sonotubes”. I suspect there is “dead space” near the edge, possibly because of graphite reflector blocks around the edge of the pressure vessel. Remember that the Sandia doc has half of the 600t of graphite for “Reflector”.

    You can see a perimeter dead zone in the IC Yongbyon reactor photo, and in this UK Magnox.

    The spare “sonotubes” are not conclusive, for 2 possible reasons. 1) They aren’t the real thing, just shapes to form a tube when the concrete is poured, then they are gash, so a few spares is no big deal. 2) The Yongbyon Upper Concrete Shield is 4.5m thick, and the “sonotubes” don’t look that long – I suspect a second layer of them would be required when the concrete is half poured, and the spares could be for that.

  14. FSB

    Andy,
    a start would be to release the rest of the supposedly many fotos. How about one that jives with one of the high windows for instance?

    I am not saying they are for sure faked, but do not put this beyond the Mossad.

    Re. the “de jure” state of war between Syria and Israel, do you think the international response would have been similar if Dimona was bombed by the Syrians? It in fact almost was by the Soviets in the Yom Kippur war I believe.

    I am saying if you want a viable arms control regime you must have as its pre-requisite a semblance of justice and equality.

    At the very least, the US should divorce itself from these Israeli misadventures as it makes us a target of terrorism. Let Israel fight with its own $ and people.

  15. J House (History)

    Assuming the interior photos were ‘faked’, where would that leave us?
    -A building roughly the size of the NK reactor was built in the eastern desert along the Euphrates, far from prying eyes over the past 6+ yrs
    -A pumping station and cooling pipes were also present, running to and from the building proper
    -The building was shielded from ground-based observation, using earthen berms
    -Israel risked war with Syria to level it in a night raid
    -Syria covers up the entire site within weeks, erects a new building and says nothing, nor retaliates
    -Syria refuses IAEA inspections amd admits nothing
    -US IC then shows a presentation months later with photo evidence it is a nuclear reactor built with NK assistance, including photos presumably taken on site during various construction phases

    You would have to accuse the US IC of deliberately lying, FSB.
    The dithered post-strike imagery shows what appears to be the top of the reactor with the roof of the containment building blown away
    -The other photos clearly show a reactor/reactor vessel under construction.

    But, where did Syria get the EU?NK?
    Just how much (undeclared) EU does NK have to sell?

  16. Shual (History)

    This may be only a bad day for the Jpost [first they wrote that Hamas stole 60 liters fuel and changed it later to 60 000 liters..] And then they showed a photo: “An aerial view of the site of Syria’s alleged reactor” of AP origin. Its gone now.

    http://shual.blogspot.com/2008/04/jpost-photo.html

    Any idea where THIS site is?

  17. Yale Simkin (History)

    Jeffrey asked:

    The thing I don’t get is that the IC diagram shows the 4-6-8 construction for a total of 61 entry ports. 52+9.
    How do you assess that?

    Some possibilities:

    1) My idle speculations of a 4+6+8+10 are not only idle, but also quite wrong.

    OR

    2) Asuming that the larger grid is real, the guvamint, after being seriously burned previously, is only showing what they can (or will) publicly prove.

    — a) the pattern shown in the interior snapshot (taken by a Druze tribesman, I speculate) is all they have – even if it is of an unfinished incomplete array. Therefore that is what they will use in the Dog and Pony Show.

    — b) They do have later images (or solid information) with a different pattern, but they won’t release them. So they won’t create a graphic with information that they won’t back up.

    — c) The released images are what they provided to the graphics designers and that is what they used to create the presentation animations.

    What I find interesting is that Yossi, using the larger grid, calculates a core that matches NK, which is what the Hayden claims.

    I dunno..

    Unless we get more data, we simply have to choose the demonstrable facts – the 4-6-8, or the version that just seems more natural to me – but cannot be proven.

    Just for convenience sake I am reposting a MAGNOX image:

  18. alphabeta

    Were the internal photos we see taken inside Yongbyon? This is a very important question as the CIA method of tying the internal photos to overhead photos will identify any building with a suitable window and vent combination as a boxed Yongbyon clone if given internal photos of Yongbyon itself!

    Imagine for a moment a Nork engineer who have access to Yongbyon photos and is considering defection. He is approached by Mossad who is looking for evidence on a possible Nork reactor built in Syria. The Nork engineer knows that Yongbyon photos are worth nothing but if presented as a Syrian reactor he can charge millions of dollars for them.

    Once such a mistake is made the US and Israel would want to keep it going in order not to lose face in the Arab world. Moreover, Israel is obsessed by a deep desire to appear omnipotent, all knowing and all capable and uncovering such a mistake at a critical time would seem intolerable.

    If this seems like a far fetched speculation take a look at this Haaretz article which says that a court order forbids an exposure about the strike being an “enormous failure”:

    http://www.haaretz.com/hasen/spages/909310.html

    It’s interesting to note that in spite of Haaretz success in court nothing like this was ever published.

    In order to conclude that the Syrians built a reactor we must first PROVE the internal photos were not taken inside Yongbyon!

  19. Yossi, Jerusalem

    I wish the Magnox experts (Rwendland and Carey Sublette) would check the calculations and especially:

    * Resolve the difference between “effective core diameter” and “core diameter”
    * Check if Yongbyon data really shows that every access port covers a 3×3 array of fuel (or sometimes control) channels

    Summary of calculations on CIA reactor size:

    Assuming maximal row of 8 access ports
    core diameter: 0.609*8 = 4.87m
    pressure vessel height: 2*2.2 + 2*5.6 = 15.6m

    Assuming maximal row of 10 access ports
    core diameter: 0.609*10 = 6.09m
    pressure vessel height: 2*2.8 + 2*5.6 = 16.8m

    Assuming maximal row of 11 access ports (a check)
    core diameter: 0.609*11 = 6.7m
    pressure vessel height: 2*3 + 2*5.6 = 17.2m

    Yongbyon data from Sandia report
    EFFECTIVE core diameter: 6.43m
    pressure vessel height: 16.8m

    * The diameter calculations are supposed to be pretty accurate, say a few percent. The height calcs are worse, probably about 5-10% error.

    * Yale tends to think they were in the process of adding another ring of access ports so the relevant data is in the 10 max row entry.

    * Please note that the encircling frame in the core top photo is perforated not solid and therefore can’t be a casting mold. The CIA caption saying the photo was taken before the concrete was poured may be a mistake. We can’t be absolutely sure they weren’t going to add more and more access port rings unless we find what the circle frame was used for.

    * An interesting point is whether we can role out the photos were taken at Yongbyon at some stages of its construction. If we can’t role it out the conspiracy theorists will keep on pestering our beloved countries. I think alphabeta misinterprets the Haaretz article, it meant to say the “enormous failure” was government confidence that Asad would retaliate and so the secrecy was really not needed, a typical court argument in such a case.

  20. FSB

    J House:

    again, I am not saying with 100% certainty the Israelis provided faked photos to US Intelligence, only that I would not be surprised at all to learn of this. Further, as “alphabeta” points out, the Israelis themselves could have been duped by whomever was their mole.

    As for your points:

    -A building roughly the size of the NK reactor was built in the eastern desert along the Euphrates, far from prying eyes over the past 6+ yrs

    ==> Yes, it was admittedly military by the Syrians and perhaps even secret, but why does that make it nuclear?

    -A pumping station and cooling pipes were also present, running to and from the building proper

    ===> Where are the pipes?

    -The building was shielded from ground-based observation, using earthen berms

    ===> As a military building should be.

    -Israel risked war with Syria to level it in a night raid

    ===> Israel would happily do this to send a message to Iran; or, as “alphabeta” sez, the Israelis themselves were misled.

    -Syria covers up the entire site within weeks, erects a new building and says nothing, nor retaliates

    ===> Oh, you can be sure they will retaliate, on their schedule, as they have said. There may have been other illicit Syrian-NK dealings going on, such as Scud related, or even maybe chemicals.

    -Syria refuses IAEA inspections amd admits nothing

    ===> They may well have been doing other illicit crap.

    -US IC then shows a presentation months later with photo evidence it is a nuclear reactor built with NK assistance, including photos presumably taken on site during various construction phases

    You would have to accuse the US IC of deliberately lying, FSB.

    ====> No. Not at all. I am saying the Israelis may be lying, or they were lied to. The US Intel is putting together a jigsaw puzzle handed to them expertly.

    The dithered post-strike imagery shows what appears to be the top of the reactor with the roof of the containment building blown away

    ====> It shows a circular crater, as would be expected from a bomb dropped after the roof was blown off by a prior bomb. This is how this is done.

    -The other photos clearly show a reactor/reactor vessel under construction.

    ===> Your arguments are charmingly circular: we are trying to address whether or not these are fakes or have been fed to US by Israelis, or to Israelis by their mole.

    So, there is no public evidence yet linking the inside photos to the xbox (ex-BoE).

  21. Carey Sublette (History)

    The design of the Yongbyon graphite pile is as follows:

    The actual cylindrical core (i.e. the complete fuel lattice) has a diameter of 6.43 m and a height of 5.9 m (from the Sandia doc). This cross section area of this is 32.5 m^2, which is precisely the same as an 812 cell lattice with 20 cm per cell. The channel diameter is 6.5 cm (p. 69, UCRL-ID-142036) giving a total core volume of 192 m^3, of which 16.1 m^3 is channel volume. With a reactor graphite density of 1.65 we have a moderator mass of 290 tonnes, within 5% of the quoted 300 tonne mass.

    Surrounding the core is the reflector which extends to the inner edge of the 8.8 m I.D. steel reactor vessel. This has a cross section of 28.3 m^2 (minus the core) and is 6.4 m high for a solid volume of 181 m^3, plus the 0.25 m reflector cap on the top and bottom of the core (16.2 m^3) for a total volume of 197 m^3, and a total mass of 325 tonnes. 290 + 325 = 615, within 2.5% of the quoted 600 tonne total graphite mass.

    I went through this exercise to make the following point about the reactor design: there is a 1.19 m gap between the core and the 4 inch steel reactor vessel, which is filled with the reflector. This gap is about 2 times the access tube spacing.

    If you look at the al Kibar core picture you see a cylindrical wall around the tube assembly, that is separated from the nearest tube by about 2 times the tube spacing.

    This wall is the steel reactor vessel. There is no room for another ring of tubes to be installed, the tube assembly is complete. Outside the vessel we see the reinforcing framework for the concrete shield.

    The core cross section appears to be (8/11)^2 = 0.53 the area of Yongbyon. If we make a plausible assumption that it has an identical core height, then that is also its is core volume fraction compared to Yongbyon.

  22. Yossi, Jerusalem

    An improvement to the core diameter calculation.

    Previously it was the distance between the access points at the ends of the longest line plus one more inter port distance. A more reasonable measure would be the distance between the two farthest fuel/control channels.

    Final summary of calculations on CIA reactor size:

    Assuming maximal row of 8 access ports
    core diameter: 0.609*(8-1) + 0.406 = 4.669m
    pressure vessel height: 2*2.2 + 2*5.6 = 15.6m

    Assuming maximal row of 10 access ports
    core diameter: 0.609*(10-1) + 0.406 = 5.887m
    pressure vessel height: 2*2.8 + 2*5.6 = 16.8m

    Assuming maximal row of 11 access ports (a check)
    core diameter: 0.609*(11-1) + 0.406 = 6.496m
    pressure vessel height: 2*3 + 2*5.6 = 17.2m

    Yongbyon data from Sandia report
    EFFECTIVE core diameter: 6.43m
    pressure vessel height: 16.8m

    The 11 port row check is now closer to the effective diameter of Yongbyon (larger by 1%). Its corresponding pressure vessel height is larger by only 2.4%.

  23. Carey Sublette (History)

    Follow up to my previous post, discussing a few assumptions.

    In assessing the size of al Kibar (with the (8/11)^2 computation) I am assuming the the size of the access tubes, and their spacing is the same as in Yongbyon. If this reactor is in fact a derivative of Yongbyon, then this is a reasonable assumption. You can vary the overall lattice size in a reactor variant without any retooling and no real core redesign (jut add or delete lattice cell rows and access tubes as needed). But if you change the size of the tubes and their relationship to the lattice, then everything needs to be redesigned and retooled.

    Also, since the core is cylindrical, it suffices to estimate its width (by counting tubes across), not counting the total number of tubes (some of which will be under-served by channels, depending on where the lattice edge falls).

  24. Yale Simkin (History)

    Carey wrote:

    If you look at the al Kibar core picture you see a cylindrical wall around the tube assembly, that is separated from the nearest tube by about 2 times the tube spacing. …There is no room for another ring of tubes to be installed, the tube assembly is complete

    Which tube are you using for the “nearest tube”?

    If it is from an 8-tube row, then no more rings are possible.

    If it is from the TEN-tube row, the outer ring is not yet complete, with only two tubes in place – the end ones from the row just right-of-center.

    If you are using the 8-tube row, then 4 tubes (the 10-tube row ends plus the 2 end- tubes from the centerline triplet) are installed outside that maximum diameter. What is the situation with them? (Possibly some type of service or sensor ports? Or maybe they are not actually installed and are simply temporary supports)

  25. Yossi, Jerusalem

    Carey Sublette (CS) have some very interesting contributions.

    The core top photo:

    CS kills the most promising conspiracy theory saying the tube assembly is complete and there is no room for another ring. This photo can’t be Yongbyon in any stage of construction.

    The cylindrical wall we see around the tube array is the upper edge of the steel pressure vessel. I guess it’s perforated because it’s supposed to be embedded inside the concrete top. Since we see the same stuff between the tubes it probably means the pressure vessel doesn’t go all the way on top and the concrete is there in contact with the hot CO2.

    Reactor power (and Pu production rate):

    CS said in a previous post that it’s reasonable to compare this reactor and Yongbyon by core volume ratio. The value he computes is 53%. A more accurate value may be closer to 50%. It seems that Hayden overestimated this reactor capabilities by about a factor of 2.

    The reactor size means the Syrians were content to produce their nuclear weapons slowly and have less of them. Apparently they didn’t plan to compete with the size of the Israeli very large nuclear arsenal and adopted a Chinese like policy of minimal deterrence, assuming of course they got fuel for the reactor, a re-processing facility and a weapon lab. Hersh says they decided their chemical warfare arsenal was useless in deterring Israel from attacking them at will so they probably thought an atomic bomb may help.

  26. Carey Sublette (History)

    Yale:
    Which tube are you using for the “nearest tube”?

    The end tubes of the central 8 tube row.

    There appears to be a regular grid of identical access tubes in a 4-6-8-8-8-8-6-4 pattern. A circular lattice calls for a regular square access tube grid.

    The spacing of the ends of these rows vs the apparent reactor vessel wall is correct for a Yongbyon-like reactor.

    The additional tubes you see: 3 of which are placed down the center in an off-grid position, and a few near the periphery, would presumably be – as you say – some other control, service or sensor access function.

  27. Yale Simkin (History)

    Yossi,
    Your 10-row LEGO option has a core 100% of the Yongbyon height and 92% of the the NK diameter.

    Rwendland wrote:
    I doubt that there is another ring of “sonotubes”. I suspect there is “dead space” near the edge… The spare “sonotubes” are not conclusive, for 2 possible reasons. 1) They aren’t the real thing, just shapes to form a tube when the concrete is poured, then they are gash, so a few spares is no big deal. 2) The Yongbyon Upper Concrete Shield is 4.5m thick, and the “sonotubes” don’t look that long – I suspect a second layer of them would be required when the concrete is half poured, and the spares could be for that.”

    I assumed that the tubes were temporary – thats why I call them sonotubes a generically used tradename for cardboard tube concrete forms – and I see more than a “few”.

    I am also making a different assumption as to where this picture is being taken.

    I do not see this as the top of the bioshield itself. It may be the pour area for the working platform above the standpipes over the fuel channels and much thinner than than the bioshield:
    (the red box outlines the location)

    After the “sonotubes” are emplaced, more rebar will fill the central ring and the floor area outside the ring. Then concrete will fill to the level of the ring top and the bottom of the niche on the right side of the back wall.

    – Or not…

  28. Carey Sublette (History)

    Yossi:

    The cylindrical wall we see around the tube array is the upper edge of the steel pressure vessel. I guess it’s perforated because it’s supposed to be embedded inside the concrete top. Since we see the same stuff between the tubes it probably means the pressure vessel doesn’t go all the way on top and the concrete is there in contact with the hot CO2.

    I should address the issue of the pressure vessel, which I skimmed over. In Yongbyon it is 4 cm thick but only needs to hold a pressure of 6 bars (i.e. atmospheres, 88 psi). I don’t know for a fact how Yongbyon was constructed, but a pressure container of this large size and comparatively low pressure can be conveniently constructed by welding steel plates together through conventional techniques. It does not appear that the vessel in the picture has actually been built up all the way yet (maybe they haven’t even started).

  29. Yale Simkin (History)

    Carey –

    This is the 10 tube row:

  30. Rwendland (History)

    I’ve tracked down the size of the Calder Hall CO2 ducts, which gives us a way do some plausability checking on the size of the BOE pressure vessel (PV) CO2 duct in this image:

    The short answer is that it is perfectly plausible that this is a smaller Calder Hall type PV, giving Yongbyon 5MWe like thermal power. For those interested the calculations are:

    Calder Hall had four 1.37m inlet ducts, and similar 4 for outlet, and runs at 100psi pressure which we have to assume is similar to BOE. So inlet duct area is 5.9 m^2.

    Working out thermal power ratio is a bit tricky, as Calder Hall was uprated from a design 180MWt to final operational 265MWt. Calder Hall was conservatively designed, so I think it’s fair to use the operational power for comparison.

    If the BOE is Yongbyon sized, then we are looking for 20MWt power. So a proportinal duct area would be:

    20/265 * 5.9 = 0.445 m^2

    As smaller ducts gives more friction, it’s reasonable to uprate this by 25% to 0.556 m^2. Assuming 2 inlet ducts for the 2 heat exchangers claimed (and looks right in the pic) that is 0.6m diameter ducts.

    Measuring the image I make the PV diameter, on the above assumptions, 9.9m (148/9 * 0.6), and the end-section height 3.4m (51/9 * 0.6).

    Counting the cooling tubes that makes the mid-section height about 4m (14/12 * 3.4).

    Assuming 2 mid sections we have a PV height of 14.8m (3.4 + 4.0 + 4.0 + 3.4).

    So we have a PV size of 9.9m diameter and 14.8m, compared with the Sandia report size estimate of 8.9m external diameter and 16.8m height for Yongbyon 5MWe. Not a perfect match, but entirely plausible for this kind of rough calculation. So from this image, the IC claim a Yongbyon 5MWe thermal power output seems plausible. Though the implied larger PV diameter makes squeezing it into the building trickier, and you would expect at least the same number of fuel channels as Yongbyon.

  31. kme

    Yossi / alphabeta:

    Another reason why the pictures are unlikely to be of Yongbyon during construction is that you can’t turn a 4-6-8 grid into a 5-7-9-11 grid without recentering the grid, and it already appears to be in the centre of the circular metal former.

    Yale:

    The outer two tubes in your 10 tube row are not laid out on the same grid pattern (they’re too close to the inner 8 tubes), so they don’t appear to be for fuel channels.

  32. Carey Sublette (History)

    Yale:

    In interpreting the image it is necessary that one keeps in mind how nuclear reactors are designed and built, and in particular how the Yongbyon reactor was designed and built. The fuel channel lattice of the core is going to be circular, and the access tubes for that lattice is going to form a square array (that is, regularly spaced tubes in an arrangement that is symmetric about the horizontal, vertical, and diagonal axes). Further we should expect to see a reflector zone around the core.

    There are a number of tubes in the image that are obviously not part of the square array and have some other function. There are three down the middle of the image, for example.

    What about the “10 tube row”? When I take a straight edge to the image the end tubes do not look like they line up exactly with the other 8 – i.e. they do not look like they are part of the square array. It is a bit less obvious than the tubes that are between rows, but it is visible.

    So what could these extra peripheral tubes be? Here’s my theory – they are access tubes for irradiation channels for experiments – or isotope production (polonium and tritium anyone?). Placing irradiation channels in the reflector zone of a reactor is a common practice.

    Building a fuel lattice out to the edge of the pressure vessel, basically dispensing entirely with a reflector blanket, is not.

  33. Allen Thomson (History)

    Could our reactor-savvy people give us some idea how plutonium production of a Yongbyon reactor ramps up with time?

    I.e., you start with a brand new reactor loaded with unburned fuel, take it through a commissioning and check-out phase. After which production commences, meaning that at some point fuel elements start being pulled on some schedule for Pu extraction and fresh ones put in their place. An increasing inventory of separated plutonium, I(t), results.

    The details and timing of the above would be of interest. Assume that the Reactor in the Box on the Euphrates first went critical on 1 Jan 2008 and took six months for check-out. What does I(t) look like after that?

  34. Carey Sublette (History)

    Allen:

    The inventory of plutonium in the reactor (in the low burn-up regime used by these types of reactors) is determined simply by the integral of power level and time. Plutonium accumulates at the rate of about 0.86 grams per MW(th)-day. The rate of extraction from the reactor is quite flexible – one can choose to get a little bit of plutonium after a short period of operation (a few months), or wait for higher concentrations to accumulate.

    The power level in Yongbyon was 0.4 MW(th)/ton of fuel. The typical degree of burn-up used for weapons plutonium is 600 MW/day, so an average operating time to get up to this “optimal” level is 1500 days.

    But the neutron flux in the core is not flat, it is highest in the middle and drops toward the edges (the thick reflector I mentioned in early posts largely serves to flatten this drop off as much as possible). So the rods in the center burn-up faster, and would be discharged with this preferred level first.

    One can choose to extract the fuel sooner. During WWII, a burn-up of 200-250 MWd was used. Proportionately more fuel must be processed of course.

    If, as we have supposed, the core volume of BoE is half that of Yongbyon, then its power level would be 10 MW(th), and it would produce 3 kg/year at continuous 100% peak power operation.

    After discharge fuel is typically cooled for at least a few months before processing.

    In a Syrian-type program they might well concentrate on building up a plutonium inventory in unprocessed fuel over the course of several years, and not have a large scale extraction capability for a quite a long time.

  35. Yossi, Jerusalem

    We have here some amazing contributions on reactor design and operation!

    I think we should retain our sceptical mode for some more time in spite of having all these nice photos. The main problems with the CIA claims may be:

    * Reactor size was like Yongbyon – A careful calculation shows core volume was half that of Yongbyon so power and Pu production rate were probably half as well.

    * Shown Nork was atomic scientist – John Bolton disagrees and the South Koreans confirm the man in the photo is Jung Tae-yang, Vice Director General of the DPRK Foreign Ministry’s 2d North American Bureau. See blowback important post in reference to: http://www.humanevents.com/article.php?id=26282&page=1

    * An artificial berm blocked view from river – Topographical data in this area is probably very bad and configuring Google Earth for best elevation interpolation wouldn’t create data when there is none. In spite of this I think the berm area is about the same level as BoE. The river area is about 50m lower so the berm was not needed unless a high Magnox refueling machine was going to be used, a chimney was about to built or there was danger of observation from the other bank.

    * BoE was not a box part of the time – All independent evidence shows BoE was always a box. However note that Hersh Syrian sources and the anonymous Israeli analyst also say BoE was not a box and was open to view from overhead.

  36. Hairs (History)

    Allen: Don’t forget that total “plutonium” includes all isotopes, therefore any given figure will contain not only the “useful” (i.e. weapons-related) isotopes such as 239 and 241, but also the more problematic ones such as 240 and 242. In particular, Pu-240, which forms by (n,gamma) reactions, has a sufficiently high spontaneous fission rate that a simple, gun-type weapon design will fizzle and fail before it becomes prompt critical.

    As stated by others, plutonium generation is a function of neutron fluence, which is approximately equal to reactor thermal power integrated over time, thus I broadly agree with Carey’s statements above. However, plutonium generation AND loss – the losses being mostly due to in-reactor fissions and conversion by absorption – are also strongly a function of neutron spectrum. Therefore some extra care has to be taken in making predictions based on previous designs (e.g. Manhattan Project, Windscale piles, Calder Hall, etc).

    For very large cores (e.g. commercial graphite moderated cores such as the UK’s present AGR reactors) the long-term evolution of the core composition can be predicted quite accurately using MCNP (Monte Carlo neutron photon) codes and assuming various flux and thermal profiles – which affect factors such as Doppler broadening of resonances – at different power levels. However, in a smaller core the flux and thermal gradients tend to be steeper. This is because they have to go from conditions at the pressure vessl wall, which by definition must be similar for all designs (or else you wouldn’t be able to use the same materials and welding techniques), to conditions at the centre of a fuel pellet, which are also the same for all reactor sizes (because you want to operate the fuel at the maximum temperature without invoking phase changes). At the same time the lattice spacing is similar for all designs because it is constrained by the moderation length of graphite. Thus your model has to deal with steeper gradients across an irreducible physical length. As a consequence you either have to significantly increase the modelling resolution, or else you have to accept greater uncertainties in the model’s results.

    In summary, the hardest bits to model well tend to be boundaries and interfaces, and these form a greater proportion of a small core than a large core. This is also the referred experience of colleagues, who say that calculations tend to become more uncertain as cores get smaller. Consequently I would be inclined to consider extrapolations from Calder Hall, and similar commercial experience, very much as an upper limit on the production of Pu-239.

    Overall I think that statements of the BOE being able to produce enough plutonium for a weapon within one year are probably more “order of magnitude” than accurate predictions. And here I don’t even touch on the subject of plutonium separation from discharged fuel, and its subsequent refinement…

    In fairness to those who gave the briefing, unless they were relying on actual figures from Yongbyon – which would be interesting in itself! – they were having to condense what one assumes is imperfect intelligence and (unavoidably) imprecise projections / extrapolations into a single figure. As far as I’m concerned, >5kg (which is about “one weapon” within a year) is pushing the bounds of plausibility – but then that’s just a technical guy’s pedantry. However, I don’t suppose that policy makers in the USA’s Congress make any distinction between 1 kg/year and 10 kg/year.

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