What is the condition of the crew at Fukushima Unit 2?

At some point in time, we will need to understand how people can discard basic thermodynamic concepts. In the latest on Unit 2, this caught my attention:

Air pressure inside the reactor rose suddenly when the air flow gauge was accidentally turned off, operator TEPCO said, adding that this blocked the flow of cooling water into the reactor, leading to full exposure of the rods.

Maybe they're tired and need some sleep. (from here)

TEPCO's charts. Still No Japanese Nuclear Armageddon Today (part III)

[ Update: Updated charts can be found here.As expected they are about to put sea water in unit 2 ]

At long last, here is some informative piece from TEPCO (via Barry's blog).

As one of Barry's commenter noted this chart is outdated as the RCIC system has failed today, that leaves them with the option of getting sea water if the decay heat is still an issue. Looks like they will be relieving pressure like they did for unit 1 and 3. 

The Sum of All Click-Throughs: An 8.9 Earthquake, a Tsunami and an Explosion at a Nuclear Power Plant

Do you think this headline is optimized for click-throughs ?

With this type of headlines how can you not think that 9500 people are casualties of a nuclear accident ?

Contrast this with the post I would have loved to write: Why I am not worried about Japan’s nuclear reactors

Fukushima Daiichi, Situations at Unit 1, 2 and 3.

From TEPCO's latest press release:

Fukushima Daiichi Nuclear Power Station:

Units 1 to 3: shutdown due to earthquake

Units 4 to 6: outage due to regular inspection

* The national government has instructed evacuation for those local residents within 20km radius of the site periphery.

* The value of radioactive material (iodine, etc) is increasing according to the monitoring car at the site (outside).

* Since the amount of radiation at the boundary of the site exceeds the limits, we decide at 4:17PM, Mar 12 and we have reported and/or noticed the government agencies concerned to apply the clause 1 of the Article 15 of the Radiation Disaster Measure at 5PM, Mar 12. After that, the radiation dose at the monitoring post decreased once. Today, the measured value revamped and the radiation dose measured at site boundary exceeded the limiting value again. As such, at 8:56AM, today, it was determined that a specific incident stipulated in article 15, clause 1 occurred and at 09:10AM, today, notified accordingly.

* In addition, a vertical earthquake hit the site and big explosion has happened near the Unit 1 and smoke breaks out around 3:36PM, Mar 12th.

* Unit 1: We started injection of sea water into the reactor core at 8:20PM, Mar 12 and then boric acid subsequently.

* Unit 2: Reactor has been shut down and Reactor Core Isolation Cooling System has been injecting water to the reactor. Current reactor water level is lower than normal level, but the water level is steady. After fully securing safety, we are preparing to implement a measure to reduce the pressure of the reactor containment vessels under the instruction of the national government.

* Unit 3: High Pressure Coolant Injection System automatically stopped. We endeavored to restart the Reactor Core Isolation Cooling System but failed. Also, we could not confirm the water inflow of Emergency Core Cooling System. As such, we decided at 5.10AM, Mar 12, and we reported and/or noticed the government agencies concerned to apply the clause 1 of the Article 15 of the Radiation Disaster Measure at 5:58AM, Mar 13. In order to fully secure safety, we operated the vent valve to reduce the pressure of the reactor containment vessels (partial release of air containing radioactive materials) and completed the procedure at 8:41AM, Mar 13 (successfully completed at 09:20AM, Mar 13). After that, we began injecting water containing boric acid that absorbs neutron into the reactor by the fire pump from 09:25AM, Mar 13.

* We continue endeavoring to secure the safety that all we can do and monitoring the periphery.

Looking back at the previous press release, they now talk about the failure of one of the cooling systems (unit 3). The borated water quenches any chain reaction so that this water cools the decay heat from the reactor and also stops any potential chain reaction from occurring. Here are some guesses from some folks working in nuclear power plants on what happened for the explosion on top of unit 1 yesterday (i.e. hydrogen or pressure explosion), again those are just guesses.  But as far as I can tell there is no way anybody can say anything about the inside conditions of any of the three cores. In particular, the wording Partial Meltdown seems to be overly used in the media when in fact the fuel rods may have been just damaged. It is indeed a serious situation but there is no need to be hysterical about it mostly because of the containment around the vessel that houses the reactor core. By the way, they seem to have used pure water not sea water in unit 3 showing to me that they seem to very much control that aspect of the process.

When this is over, I'll be buying the book on how the operators went about sustaining a 8.9 earthquake and a tsunami.

Still No Japanese Nuclear Armageddon Today (part II)

The new TEPCO press release provides additional insight into the current situation. Out of all the power plants, one that seems to be the most problematic is unit 1.

All 6 units of Fukushima Daiichi Nuclear Power Station have been shut down.
Unit 1(Shut down)
- Reactor has been shut down. However, the unit is under inspection due to  the explosive sound and white smoke that was confirmed after the big quake occurred at 3:36PM.
- We have been injecting sea water and boric acid which absorbs neutron into the reactor core. 

Other sources seem to confirm that the reactor containment vessel has not been breached which allows the second step highlighted above: i.e. flood the containment with water to continue the cooldown of  the decay heat. The use of borated water is unusual in that boron is never used in Boiling Water Reactor's (BWR, looks like a GE design) coolant.  Boron is a neutron poison that stops any chain reactions very quickly as it has a very large cross section for thermal neutrons (the particles enabling chain reactions).. Some of that boron may come from a US source. I am guessing that they want to be on the safe side besides cooling the reactor core. That also means that this reactor will be out of business for a long while. One can also read about the two other units:

Unit 2(Shut down)

- Reactor and Reactor Core Isolation Cooling System have been shut down.

Current reactor water level is lower than normal level, but the water level is steady. After fully securing safety, we are preparing to implement a measure to reduce the pressure of the reactor containment vessels under the instruction of the national government.

Unit 3(Shut down)

- Reactor has been shut down and we continue injecting water by High Pressure Core Injection System. After fully securing safety, we are preparing to implement a measure to reduce the pressure of the reactor containment vessels under the instruction of the national government.

- Currently, we do not believe there is any reactor coolant leakage inside the reactor containment vessel.

If I read this correctly, the current main concerns are therefore for units 1 and 2 with unit 1 being the most concerning. From their description, it looks like they have the means of cooling these units. 

Still No Japanese Nuclear Armageddon Today

According to the BBC, the Japanese Nuclear Regulatory Agency has rated this accident as a level 4 on the IAEA INES scale and seems to mention that the containment has not been breached which is consistent with the previous interpretation of TEPCO's press release. Let me be specific, this containment is one of the key difference between a Chernobyl type of reactor and the light water reactors being used in Japan.

If this is a level 4 accident, then a similar incident occurred in France at the nuclear power plant in Saint Laurent des Eaux in 1980 as a cooling incident led to the melting of one channel of fuel in the reactor. There was no release outside the site. The fuel rods were eventually removed. Nobody was hurt. If things have been done properly, I would not be surprised if this accident at Fukushima is eventually de-rated when we discover the real physical interior of the core. By the way, that French power plant is was still producing power to the electric grid for 23 years after this accident.

There is no Japanese Nuclear Armagedon today.

More technical information from can be found here.

No Japanese Nuclear Armageddon Today

I am a Nuclear Engineer by trade and I am not sure I see a reasonable coverage of the current situation going on in Japan. For instance this type of reporting is bad (I mean come on, using Ukrainian "specialists" as experts and compare the Japanese plants to the RBMK reactors in Chernobyl is just unconsciounable.). I am not working for TEPCO or any of its affiliates or any nuclear related entities but here is my take and explanation of their latest press release:

Press Release (Mar 12,2011)
Impact to TEPCO's Facilities due to Miyagiken-Oki Earthquake (as of 3PM)


Below is major impact to TEPCO's facilities due to the Miyagiken-Oki Earthquake that occurred yesterday at 2:46PM.

*new items are underlined

[Nuclear Power Station]
Fukushima Daiichi Nuclear Power Station:
Units 1 to 3: shutdown due to earthquake
Units 4 to 6: outage due to regular inspection

Good only three power plants to pay attention to.

* The national government has instructed evacuation for those local residents within 10km radius of the periphery.

I am guessing this is a conservative move by the authorities. Nothing more.

* Measurement of radioactive material (Iodine, etc.) by monitoring car indicates increasing value compared to normal level. One of the monitoring posts is also indicating higher than normal level. We will continue monitoring discharge of radioactive material from exhaust stack and discharge canal, etc.

Higher than normal does not mean it is unsafe in one post. In particular, I am guessing the language would be different if the levels were above "safe" levels ( by safe I mean as set by national standards, i.e. it does not mean that one gets sick, but that's a different story). Now let's get to the meat of the press release:

* Reactor of Unit 1 has been shut down and steam in reactor has been cooled by isolation condenser, but it is now stopped. Because pressure level in reactor containment vessel is increasing, following the national government instruction, we have done the measure to reduce the pressure of the reactor containment vessels in order to fully secure safety and we understand that we have succeeded it at 2:30PM.
At present, reactor water level is becoming lower and we are injecting water accordingly.
* Reactor of Unit 2 has been shut down and we continue injecting water by Reactor Core Isolation Cooling System. Current reactor water level is lower than normal level, but the water level is steady. Following the national government instruction, we are preparing to implement a measure to reduce the pressure of the reactor containment vessels in order to fully secure safety.
* Reactor of Unit 3 has been shut down and we continue injecting water by Reactor Core Isolation Cooling System. Following the national government instruction, we are preparing to implement a measure to reduce the pressure of the reactor containment vessels in order to fully secure safety.

The main problem with shutting down a reactor is generally not in shutting down the neutron population (criticality issues) in the core but rather after that has been done, it is to remove the remaining heat produced by the decaying reactor core. The heat produced by the core is large but it is decaying. All safety systems in a reactor plant are designed to address specifically that issue. What is said above is that the three cooling systems are in play to remove that decay heat. What this also says is that the control rods have done their jobs and now we have a cooling issue only. The issue to pay attention to is whether the cooling systems would fail. I don't see any of that in the press release.  Over time, this issue is slowly going away as the reactor decay heat decreases.

* We are implementing a measure to reduce the pressure of the reactor containment vessels, but, one of our employees working in the Unit 1 was irradiated at over 100mSv level(106.3mSv). He received a medical treatment by a special physician.

The high pressure is just a side effect of that large amount of heat released in the containment section of the core. With regards to the employee receiving 106mSv, that's 10.6 rem, he has received less than 50 times  the annual dose of a radiation worker. See here in the Health Physics Society website:

The most recent report (November 1999) indicates that the average annual measurable dose to a radiation worker at a commercial nuclear power plant in 1998 was 180 millirem.

That dose is also twice the legal limit for a year as defined by the U.S. Nuclear Regulatory Commission:

Dose Limits for Radiation Workers

Title 10, Part 20, of the Code of Federal Regulations (10 CFR Part 20), "Standards for Protection Against Radiation," establishes the dose limits for radiation workers. Although the limits vary, depending on the affected part of the body, the annual total effective dose equivalent (TEDE) for the whole body is 5,000 mrem (5 rem).

So it looks like he is going on some extended paid vacation by TEPCO as a result but tit is very likely not lethal  Let us go back to the press release:

Fukushima Daini Nuclear Power Station:

Units 1 to 4: shutdown due to earthquake

* The national government has instructed evacuation for those local residents within 3km radius of the periphery and indoor standby for those local residents between 3km and 10km radius of the periphery.

same as before. Authorities are being conservative.

* At present, we have decided to prepare implementing measures to reduce the pressure of the reactor containment vessel (partial discharge of air containing radioactive materials) in order to fully secure safety. These measures are considered to be implemented in Units 1, 2 and 3 and accordingly, we have reported and/or noticed the government agencies concerned.

* Unit 3 has been stopped and being "nuclear reactor cooling hot stop" at 12:15PM.

Out three units, one has its decaying heat been removed. The two other plants continue the process of removing the decaying heat from the core.

Kashiwazaki Kariwa Nuclear Power Station:
Units 1, 5, 6, 7: normal operation
Units 2 to 4: outage due to regular inspection

Good news.

[Thermal Power Station]
Hirono Thermal Power Station Units 2 and 4: shutdown due to earthquake
Hitachinaka Thermal Power Station Unit 1: shutdown due to earthquake
Kashima Thermal Power Station Units 2, 3, 5, 6: shutdown due to earthquake
Ohi Thermal Power Station Units 2, 3: shutdown due to earthquake
Higashi-Ohgishima Thermal Power Station Unit 1: shutdown due to earthquake

If anything this is not good with regards to providing some electrical baseload to the national grid.

[Hydro Power Station]
4 stations in Fukushima Prefecture were shutdown due to earthquake.
Power stations in Yamanashi Prefecture have been restored.

[Transmission System, etc.]
5 substations shown below have been shutdown:
- Naka Substation
- Shin Motegi Substation
- Joban Substation
- Ibaraki Substation
- Nishi Mito Substation

[Blackout in TEPCO's Service Area]
Total of about 0.6 million households are out of power.
Tokyo: 0
Kanagawa Pref.: 0
Tochigi Pref.: 30,389
Chiba Pref.: 36,456
Saitama Pref: 0
Gunma Pref.: 0
Ibaraki Pref: 537,288
Yamanashi Pref: 0
Shizuoka Pref: 0 (east of Fuji River)

[Supply and Demand Status within TEPCO's Service Area to Secure Stable
Power Supply]
Backup supply from Shinshinano Conversion Station: 600MW
Backup supply from Sakuma Conversion Station: 300MW
Backup supply from Higashi Shimizu Conversion Station: 100MW

Because TEPCO's facilities have been seriously damaged, power shortage may occur. TEPCO appreciates customers' cooperation in reducing electricity usage by avoiding using unnecessary lighting and electrical equipment.

With all the thermal power stations off-line, no wonder they are asking people to curb their use of electricity.

We are taking all measures to restore power, however, we expect extremely difficult situation in power supply for tomorrow as well. We kindly ask our customers to cooperate with us in reducing usage of power.

Please do NOT touch cut-off electric wires.

Words of wisdom!

CS: Compressive Diffuse Optical Tomography, OMP based compressed sensing reconstruction for dynamic MRI, K-t group sparse

Jong Chul Ye just sent me the following:

Hi Igor,

I would like to bring your attention to our new paper which will appear in IEEE Trans. on Medical Imaging.

O. Lee, J.M. Kim, Y. Bresler, and J. C. Ye, "Compressive Diffuse Optical Tomography: Non-Iterative Exact Reconstruction using Joint Sparsity," IEEE Trans. Medical Imaging, Special issue on "Compressive sensing for biomedical imaging", 2011 (in press).

The novelty of this work is to demonstrate that compressed sensing is not only useful to improve resolution in diffuse optical tomography, but also helpful to overcome the nonlinearity of inverse scattering problem, which is originated from diffuse wave propagation. Accordingly, we can provide a non-iterative and exact reconstruction algorithm for diffuse optical tomography without resorting to Born-type approximation and iterative use of computationally expensive PDE solvers. The key theoretical ingredient to enable this work is a new-type of CS solver for joint sparse recovery based on recently discovered generalized MUSIC criterion. We believe that this type of approach can be extended for general inverse scattering problems such as radar, microwave imaging, optics, and etc.

I would be happy to hear any feedback from you !

Best regards,

-Jong

Solving the nonlinear diffusion equation is a great achievement! Let me just say that I am going to read it over the week-end to digest how this implementation of MUSIC is doing the work. One tiny thing, equations (2) and (3) are approximations of the linear transport equation which itself has been looked into with some l_1 minimization approach. 

Here is the paper: Compressive Diffuse Optical Tomography: Non-Iterative Exact Reconstruction using Joint Sparsity by Okkyun Lee, Jong Min Kim, , Yoram Bresler and Jong Chul Ye. The abstract reads:

Diffuse optical tomography (DOT) is a sensitive and relatively low cost imaging modality that reconstructs optical properties of a highly scattering medium. However, due to the diffusive nature of light propagation, the problem is severely illconditioned and highly nonlinear. Even though nonlinear iterative methods have been commonly used, they are computationally expensive especially for three dimensional imaging geometry. Recently, compressed sensing theory has provided a systematic understanding of high resolution reconstruction of sparse objects in many imaging problems; hence, the goal of this paper is to extend the theory to the diffuse optical tomography problem. The main contributions of this paper are to formulate the imaging problem as a joint sparse recovery problem in a compressive sensing framework and to propose a novel non-iterative and exact inversion algorithm that achieves the l0 optimality as the rank of measurement increases to the unknown sparsity level. The algorithm is based on the recently discovered generalized MUSIC criterion, which exploits the advantages of both compressive sensing and array signal processing. A theoretical criterion for optimizing the imaging geometry is provided, and simulation results confirm that the new algorithm outperforms the existing algorithms and reliably reconstructs the optical inhomogeneities when we assume that the optical background is known to a reasonable accuracy

Muhammad Usman pointed out two of his recent papers: A computationally efficient OMP based compressed sensing reconstruction for dynamic MRI by Muhammad Usman, Claudia Prieto, Freddy Odille, David Atkinson, Tobias Schaeffter and Philip Batchelor. The abstract reads:

Compressed sensing (CS) methods in MRI are computationally intensive. Thus, designing novel CS algorithms that can perform faster reconstructions is crucial for everyday applications. We propose a computationally efficient orthogonal matching pursuit (OMP)-based reconstruction, specifically suited to cardiac MR data. According to the energy distribution of a y–f space obtained from a sliding window reconstruction, we label the y–f space as static or dynamic. For static y–f space images, a computationally efficient masked OMP reconstruction is performed, whereas for dynamic y–f space images, standard OMP reconstruction is used. The proposed method was tested on a dynamic numerical phantom and two cardiac MR datasets. Depending on the field of view composition of the imaging data, compared to the standard OMP method, reconstruction speedup factors ranging from 1.5 to 2.5 are achieved.

K-t group sparse: a method for accelerating dynamic MRI by Muhammad Usman , Claudia Prieto, Tobias Schaeffter and Philip Batchelor. The abstract reads:

Compressed sensing (CS) is a data-reduction technique that has been applied to speed up the acquisition in MRI. However, the use of this technique in dynamic MR applications has been limited in terms of the maximum achievable reduction factor. In general, noise-like artefacts and bad temporal fidelity are visible in standard CS MRI reconstructions when high reduction factors are used. To increase the maximum achievable reduction factor, additional or prior information can be incorporated in the CS reconstruction. Here, a novel CS reconstruction method is proposed that exploits the structure within the sparse representation of a signal by enforcing the support components to be in the form of groups. These groups act like a constraint in the reconstruction. The information about the support region can be easily obtained from training data in dynamic MRI acquisitions. The proposed approach was tested in two-dimensional cardiac cine MRI with both down-sampled and undersampled data. Results show that higher acceleration factors (up to 9-fold), with improved spatial and temporal quality, can be obtained with the proposed approach in comparison to the standard CS reconstructions.

It's Not Me, It's You

In the past two days, I sent some requests out for some papers/preprints. Invariably, I get a very kind email back with the attendant paper and a word saying that the author like the blog. As much as I can feature papers that are behind a paywall, I don't like it. I am going to go with the opposite of George Constanza on this one: It's not me, it's you, Sure, I could read your paper and be thrilled, but what about those 50 to 500 potential readers that the blog can provide to your paper ?. I want you to be a rock star, not some curiosity behind some walled garden. If you think you cannot put your work on your personal web site, then please reconsider your position in light the Sherpa/Romeo database. This database provides a summary of your self-archiving rights. For instance, here is the result for the American Astronomical Society or the Optical Society of America. Given that, you might also be interested in patronizing the green publishers for your next paper. Remember even your future employer or your tenure track committee know how to search on the web these days. What are you waiting for ?

Related advice: Nobody Cares About You and Your Algorithm

Around the blogs in 80 hours.

I haven't done this in a while but here a series of blog entries that got my interest. 

Vladimir: Global and China Camera Module Market, 2010-2011, CMOS to Overtake CCD in DSCs by 2013 So in effect, a technology born in the mid-1990's (CMOS) is now overtaking another one (CCD). This is amazing.

Zhilin: Misunderstandings on Sparse Bayesian Learning (SBL) for Compressed Sensing (1)

Bob: Artifacts in Greedy Pursuits: A Brief History, More thoughts on OMP performance limits from SIC

Alex: An identity for the divisor function

Terry: Topics in random matrix theory

Yaroslav: Linear Programming for Maximum Independent Set

Victoria: Open peer review of science: a possibility CS is a small world, Victoria has published on CS and she mentions both Donoho and Trebino in her blog entry. We had a small Q&A with Rick Trebino a while ago.This issue of science publication is also a common theme some of us discuss on Twitter with the #sciencepub tag.

Randy: Extremely High Refractive Index Terahertz Metamaterial, Enhancing Terahertz scanners using Compressive Sensing Technology. Randy is a lawyer but he blogs on Terahertz technology, who would have thought. The interesting element of Teraherz imaging is that not much is known with regards to the interaction of light with matter. In other words, the dictionary is not well known in the first place.

 . 

Martin: Accurate eye center localisation for low-cost eye tracking This is an interesting approach, but please don't say it is not machine learning, it is.

Dick: Cosmic Embryo #3: The ART Of 3D Sun And Breast Cancer Imaging

MV4U: New 3D machine vision product, Vision Troubleshooting #2, Vision Troubleshooting #1 – has it ever worked?, Troubleshooting vision the MV4U way  I like this blog as it shows the differential between how some technology is sold and how it is really implemented in real life. The remarks on that site pretty much reminds me of some acid test. For the people at the low end of the TRL scale it really points the requirements that are not being met by current technology.

Greg: Real-time through-wall imaging using an ultrawideband multiple-input multiple-output (MIMO phased array radar system, SAR Imaging of Northeastern University Campus

Hal: What are your plans between ACL and ICML?

Albert: Imagers at ISSCC (5)

Credit: NASA, Opportunity :: Navigation Camera :: Sol 2525