Japan: Temperature Soars Mysteriously Inside Fukushima Nuclear Reactor

TOKYO - The temperature of a reactor at Japan's stricken Fukushima Daiichi nuclear plant has soared and remained mysteriously high Monday, despite more water being pumped through it.

The facility's No.2 reactor had reached 164 degrees Fahrenheit (73.3 degrees Celsius) by Monday morning, after sitting at 113 degrees Fahrenheit (45 degrees Celsius) on Jan. 27, broadcaster NHK reported.

That was despite Tokyo Electric Power Company (TEPCO) officials pumping 9.6 tonnes (10.6 tons) of water through the reactor each hour -- about 10 percent more than before.

Actually it was reported in the Washington Post.

Messages show conflict within NRC after Japan’s earthquake and tsunami

The NRC e-mails reveal disagreement about how to advise the Japanese. The NRC staff chafed at some unorthodox advice coming from an ad hoc group of scientists assembled by Energy Secretary Steven Chu. Famed physicist Richard Garwin, one of Chu’s group, proposed setting off a controlled “shaped” explosion to break through the concrete shield around the primary steel containment structure to allow cooling water to be applied from the outside. One NRC scientist called the idea “madness.”

Another idea from the Chu group was to attempt a “junk shot” — a variation on what some engineers proposed to stop the oil spill in the Gulf of Mexico — to plug leaks of radioactive water from Fukushima’s nuclear reactors into the sea. When using a mixture of sawdust, newspapers and other junk failed, Japan’s Tepco ultimately used a compound known as liquid glass.

Apparently the last people we need helping on this situation right now are those tasked with the responsibility. Where is Red Adair when you need him ?

Try this URL for some good technical reporting: http://atomicpowerreview.blogspot.com/

“Tokyo Electric has been monitoring the rise of this single parameter for some time now. No other parameter changes of note have occurred. For example, gas sampling of the containment at 1F-2 has shown no alteration of note. Tokyo Electric has been adjusting injection flow rates at all three damaged reactors for some time now in order to optimize temperature control vs. buildup of contaminated water; TEPCO has also been making some alterations in systems involving injection water sources and backup pump availabilities. TEPCO’s opinion at the beginning of this trend was that one of its flow alterations (variance between feed ring flow rate, and core spray flow rate, as well as total overall flow rate) had caused some sort of flow rearrangement (this is only a paraphrase) which allowed an alteration of temperature at the one location.

“[blogger]’s first suspicion is a progressing failure of the single temperature instrument. Barring this, it is conceivable that some disarranged portion of the internal structure of the reactor itself may have moved, causing the difference in temperature indication. For example, if part of the core further collapsed against the lower RPV head, this could conceivably be possible - however unlikely it is. It is also conceivable that any volume of accumulated, solidified salt from the time period early in the accident during which salt water was being injected may have moved, causing a similar indicated event.

“Having said all of that, there is no indication at the moment that any sort of increased risk exists as to further core damage, release of material, or recriticality. Even though this last mentioned possibility is exceedingly remote, TEPCO has, on Feb. 7th, injected boron into 1F-2 reactor as a wholly precautionary measure... although [blogger points] out that at least once TEPCO has injected boric acid in an attempt to help cooling by dissolving perceived accumulated salt deposition.

“The second overall Fukushima Daiichi concern is just a repeat of an earlier one; there is a thought that 1F-4 is in danger of collapse. The spent fuel pool of this plant was supported by steel girders, during a large construction project post-accident by TEPCO, and that space surrounding the girders filled with concrete, so that the spent fuel pool is now resting on a giant steel reinforced concrete monolith. Further, TEPCO is using giant cranes to remove debris and structural material (and, thus, considerable mass) from the tops of the damaged reactor buildings at 1F-3 and 1F-4 so that the risk of any collapse is further reduced. This “fresh” risk is also thus not fresh at all; TEPCO has no present concerns about this eventuality.”

“... Tepco tried to improve cooling further by tuning the rates of water injection. On 2 February, feedwater injection was reduced by two cubic metres per hour and the core spray was stepped up by the same amount.

“Water injection from the dark blue feedwater line was reduced, while the light blue core spray was increased by the same amount

“After making this change, Tepco noted a tendency for increasing temperature at the bottom of the reactor vessel. Within a matter of hours the company decided to reverse the change and restore the previous injection rates, but the temperature continued to slowly rise.

“Two of the three temperature sensors at the bottom of the reactor vessel edged up by about 2ºC. The third, however, rose by around 20ºC to hit 72.2 degrees at 5.00am today. Tepco acted to stem this increase by injecting an extra cubic metre of water per hour through the feedwater line, and this stabilised the sensor at about 70ºC. It has since decreased to 68.5ºC, while the other two sensors were at a new low of around 41ºC.

“Tepco was able to discount recriticality as a potential cause of the temperature rise after conducting an analysis of charcoal filters in the containment gas control system. These showed very low traces of fission products that were below the threshold that would indicate criticality. Nevertheless Tepco this morning injected boric acid into the reactor vessel as a precaution and increased the core spray injection rate by three cubic metres per hour.

“The majorty of unit 2’s core is thought to have melted and slumped to the bottom of the reactor vessel, but its configuration there is unknown. What Tepco’s experience indicates is that one portion of the deformed core relies on a certain flow from the feedwater pipe for cooling. While the core spray complements feedwater input and was significant in the push to bring the temperature below 100ºC, the two are apparently not interchangeable for one specific area of unit 2’s core. Tepco has modified injection rates at all three of the melted Fukushima Daiichi reactors several times in the past without experiencing warming effects such as this.

“The current injection rates are 6.8 cubic metres per hour through the feedwater system, and 6.7 cubic metres per hour through the core spray. “

http://www.world-nuclear-news.org/RS_Stabilisation_after_Fukushima_cooling_change_0702121.html

... now confirmed by TEPCO, who are now saying that the high-reading instrument near the bottom of the reactor vessel at their 1F-2 plant is likely failed. The detector has failed a resistance check performed by TEPCO, meaning that the indication is confirmed incorrect.

It is thus safe to disregard this one outlier in terms of temperature readings at 1F-2 ...

3:30 PM Eastern Tuesday February 14, 2012

http://atomicpowerreview.blogspot.com/

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