Category Archives: Science

Hanford Reactor B

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Yesterday I went on what is pretty much a nerd tour of Hanford Reactor B. Hanford is the Department of Energy facility where they made plutonium to make nuclear bombs, and Reactor B was the first reactor built during World War II to make plutonium. It is now a National Historic Landmark. The tour included a long bus ride to the site, which gives you a better understanding of just how big Hanford is. The tour then includes several hours to wander around the building, and several presentations by docents. I still can’t quite get over the fact that the public can tour a building where they used to make plutonium, which is rather radioactive and toxic.

The science and engineering behind the facility was impressive, and I also enjoyed looking at 1940s era technology and signage. I don’t if it was that era, or the facility, or what, but there were some fun signs all over the place. There were also some hidden historical signs, like all the clocks were stopped at 10:48, which was time on the night of September 26, 1944 when the reactor achieved fission for the first time. I don’t know why, but I was amused that almost every room had a “broom” station, which were pegs on the wall where a broom and dustpan were hung. I think I only saw one room where there was actually a broom in its proper station. I guess they do less sweeping now, or they have moved onto vacuum technology.

I really appreciated that you could wander around and spend your time looking at everything. Most of the areas have decent signage to indicate what you are looking at, although the engineer that I am, I would prefer perhaps a bit more detail. My one criticism of the tour was that they completed glossed over the amount of environmental contamination created at Hanford. In an intro video we watched before taking the tour, they briefly mention that waste was buried to be dealt with later. The docent at one point said they are cleaning up the site, which is an understatement. I know enough about the site to feel like they just didn’t want to admit the contamination they caused. Signs of remediation are present in the building. There were plenty of pipes that obviously had asbestos, and the pipes had clearly been abated to encapsulate the asbestos, so it would not become airborne and thus a hazard. There were dosimeters on the walls everywhere, which were clearly been analyzed frequently.

Hanford Reactor B

Front Face where fuel rods were loaded into reactor, which is behind the front face

Warning Do Not Introduce Heat Source into any opening in reactor unit

Front face close up fittings

For security reasons, it was called the metal loader instead of uranium loader

Valve Pit Room; notice in lower right, tops have been removed from access openings; tops were removed at Russian inspectors’ request to prove no water was going through pipes as part of treaty to reduce nuclear weapons

Exhaust Fan

Wall of something in control room

Control Room, telephone switchboard equipment was used to monitoring equipment

Control Room where operator sat

Control room board with warning “Caution: bumping panel may cause scram”

Fuel Storage Basin, there used to be water underneath the wooden boards where the used fuel was stored temporarily 

Wall of old signs

Old sign (my favorite)

Total Solar Eclipse

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I came to Niagara Falls for the 2024 total solar eclipse with the idea of spectacular images of the eclipse above the falls. Unfortunately the weather did not cooperate. I was really lucky with clear skies for the 2017 eclipse, so the overcast skies was really disappointing. I got a couple of glimpses of the partial eclipse. Totality did not disappoint. It’s been seven years since I last experienced totality, but I feel like totality was more dramatic this time. It was so overcast that it was already cool and not bright, so when totality hit, it felt very much like night and was very dark.

View of partial solar eclipse through clouds

View of partial solar eclipse through clouds

View of partial solar eclipse through clouds

Niagara Falls during totality

Niagara Falls during totality (note water over falls from long exposure on this photo)

Niagara Falls with partial solar eclipse barely visible in center near top

Montreal Museum of Archaeology and History

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I am currently in Montreal for the second time. The first trip was short, but I visited the Montreal Museum of Archaeology and History, and I really liked it. This trip is also short, but I had time to visit the museum again. Most of the museum is underground in an archeological site of old Montreal. You can walk around the stone walls of buildings that used to stand on the site. The museum does a really nice job of projecting onto the ruins lines and text, so you can understand at what you are looking. They also have stairs, so you can climb on top of ruins and look down onto them without damaging them. Further, in some areas, they have lights hanging from the ceiling that light up during an audio explanation of what is at the site, so the lights emphasize what the used to be at the site based on the ruins.

Floor and walls of the former Royal Insurance building

Foundation of the former Royal Insurance building

Foundation of the former Royal Insurance building with a projection showing the inverted arch of the foundation

Foundation of the former Royal Insurance building and projection showing window of Berthelet building

Old latrine drain with projection indicating how water ran

Old pipes in archeological site

Exhibit lights suspended over archeological site to indicate what is present

Exhibit lights suspended over archeological site to indicate what is present; lights are turned off in this photograph so site is detail can be seen

Bargello Quilt

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I made my first bargello quilt. I have been exploring the different patterns that can be formed using a bargello technique. For my first, I decided to so something simple, and I designed it to look like a parabola. I also quilted it by connecting the corners of the pieces to emphasize the parabolic shape. I like parabolic shapes. Also I love fluid dynamics, and the velocity profile of laminar flow forms a parabola. While I named this quilt Parabola. I could have named it laminar flow. Also, I am a nerd.

All the fabric is from Island Batik, Gemstones and Rainbow Days series.

Parabola quilt, a bargello quilt

Parabola quilt, a bargello quilt

Parabola quilt, a bargello quilt

Bletchley Park

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As I am in London, I took a short train to Bletchley Park to see where the British codebreakers worked during World War II. I had read about this place before, so it was neat to see it in person. You can tour the mansion where they originally worker as well as most of the other buildings that were added on later. They also have exhibits explaining how they decrypted codes and machines that were built to aid in decryption. To be honest, even though I understand the basics of decryption, I still had trouble following much of what was explained. However, it was still interesting to see. Also the mansion is beautiful, and the newer buildings are pretty much what you would expect of a WWII government building.

Bletchley Park the original mansion

Bletchley Park inside

Bletchley Park ballroom

Bletchley Park offices

Bletchley Park new building

Enigma machine

While walking to the mansion, there was a fenced off area where there was a hole, so of course, I had to investigate. I’m walking around this historic site reading about cryptography, and I, being me, have to go investigate any hole in the ground, especially when pipes are involved.

Maintenance on pipes underneath

Mathemalchemy

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I finally got to National Academy of Sciences to see Mathemalchemy before it closes. The exhibit shows the beauty of the art in math, or perhaps of the math in art. I love examining the math in nature and the beauty of it. This art exhibits gave me some ideas for things that are already percolating in my head that I want to make. Possibly because I am really into sewing and quilting at the moment, the Cryptography Quilt was my favorite part. Its construction is impressive.

Mathemalchemy

Yarn and metal shapes

Nautilus

Landscape

Sea life

Seashore

Cryptography Quilt

Curio Shop

Risk Reduction Engineering for COVID-19

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In response to some discussions I had seen about the use of HEPA filters to help with the COVID-19 crises, I wrote some thoughts on how effective I thought HEPA might be. Several people on Twitter stated they agreed with my statements. An HVAC technician (@JSTootell) provided some thoughts that I had never even considered such as the energy requirements on the buildings where a HEPA filter is installed as HEPA requires more energy (i.e. electricity) to run than normal HVAC filters. He also said the normal air velocity is super low because if you increase the air velocity and hence get more circulation, people complain about the noise of the air through the vents.

Some others have noted that HEPA filters, on a whole HVAC system or portable units in each room, won’t hurt to which I agree. One said they should be a part of a multiple layer approach to prevent the spread of COVID-19 to which I also agree. In fact, while I did not say it, that is part of my argument, HEPA filters alone will not solve the problem of COVID-19 transmission. I want to take a step back though and discuss this from an engineering perspective.

The basic, general idea in engineering is you find out what your design specifications are, you make some calculations and draw some designs to comply with those specifications based on proven information, you throw in some safety factors, and then you build whatever it is to comply with your design and calculations. If you want to build a bridge, you need to know before hand what are the design specifications. Is it for trains, vehicles (cars and trucks), pedestrians, or something else entirely? How many of the intended type of users will be crossing the bridge daily? What is the span of the bridge? What is the height of the bridge? What type of weather will the bridge will be exposed to? There are far more questions, but that is the general idea. You can’t design a bridge until you know what you are designing.

I currently work in human health risk assessment related to exposure to hazardous chemicals. It is not the same as risk assessment related to exposure to infectious agents, but there are similarities. With hazardous chemicals, the goal is to reduce people’s exposure such that they are not at undue risk to the chemical exposure. You can’t reduce risk to zero; it is simply impossible. With chemicals that cause cancer, generally you are trying to get the risk below one in a million chance of cancer caused by exposure to that chemical. Another part of this is who is at most risk. With chemicals, the people we are generally most concerned with are children or pregnant women as they can be more susceptible to harmful effects than healthy, non-pregnant adults. The risk requirement is one of your design requirements. If a person can be exposed to 100 mg/l per day (via ingestion) or 100 mg/g (via inhalation) of a certain chemical and not be above one in a million risk of cancer, then you have to figure out what needs to be done at a contaminated site or with contaminated drinking water to get their exposure (and thus risk level) below that number. This could mean filtering water or removing topsoil at site (to avoid incidental ingestion of contaminated soil or to avoid breathing in soil particles). What kind of treatment and how much treatment is needed to get below that concentration? That is one of your design requirements. Similarly the design and operation of water treatment plants is based on cleaning water such that the water has less than some amount of a contaminant before it is sent via pipes to the customers. Design requirements from water treatment plants is generally based less on risk calculations and more on state and federal requirements for contaminant levels in drinking water. These federal requirements are called Maximum Contaminant Levels. Water treatment plants must meet these requirements, and they are designed to prevent the people who drink that water from getting sick from microorganisms or chemicals in the water.

This leads me to designing a HVAC system with HEPA filters or the use of portable HEPA filters in buildings to protect against COVID-19. In order to design a system, you have to know the design requirements. It is absolutely fine to say you want to reduce virus particles in the air and reduce transmission, but that is not a design requirement. Reduce is a vague, qualitative word. Engineering requires quantitative requirements. If you only want to reduce particles in the air, then you will only reduce the risk by an unknown amount with no clarity on if that reduction is an acceptable amount to the occupants of the building. Reducing risk could mean that instead of 30% of the occupants of a building getting sick, only 20% do. I personally don’t find that to be an acceptable reduction. A design requirement is based on what concentration of virus particles can be in the air and no person gets sick from COVID-19. Perhaps your requirement would not be that stringent, perhaps you would be ok with one in a thousand people getting sick from COVID-19 based on the design. The design requirement can be based on people wearing a mask or not wearing a mask. Maybe with everyone wearing a mask indoors, they can be exposed to 10 virus particles per hour, but without a mask, they can only be exposed to 2 virus particles per hour. This is where infectious disease experts are needed to provide information as to the pathogenicity and virulence of the pathogen, which in this case is COVID-19. An engineer designing a HVAC or some other filtering system for a building is not the person to decide what those design requirements are. They need the infectious disease experts to state what concentration of a pathogen a person can be exposed to without getting infected. The concentration may be zero. The problem at this point is I don’t think we know how much COVID-19 a person can be exposed to without getting sick. Thus, if we don’t know how much COVID-19 a person can be exposed to without getting sick, how can we possibly design a system to prevent a person from getting sick.

I can already hear arguments that we just need to do something. We need to accept some risk but do some things to reduce risk, so we can get things back to normal. I don’t think most business owners are going to be willing to spend a non-negligible amount of money on some design that will simply reduce risk to an unknown and unproven amount. For a place of employment or a school, is it reasonable to ask people, especially children, to return to a building with an unknown risk if a system has been put in place that reduces the risk an unknown amount? How much money should employers and educational boards spend to reduce risk an unknown amount? If you are willing to accept some risk, then why spend money on something that may reduce risk by some unknown amount? Everyone is already spending money on masks, gloves, hand sanitizer, etc. which at least has been proven to reduce risk, but not eliminate it, by a reasonable degree from a cost benefit perspective. I spent $20 or something on two reusable cotton masks that I wash after use. That is a very reasonable cost benefit amount from my perspective even though I can’t calculate the risk reduction of the mask. How much money is reasonable to invest in either a whole system HEPA filter or portable HEPA filters when the risk reduction is unknown? An extremely quick internet search provides options for portable HEPA filters from $200 to $1200. Should schools buy one per classroom, even at the low price end, when there is no data to show they would reduce risk at all? The point is, reducing risk is good, but if you going to invest money to reduce the risk, it would be prudent to determine how much the risk is actually going to be reduced before you do it.

HVAC, HEPA, and COVID-19

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I recently saw some discussions on Twitter about the usefulness of HEPA filters in schools and other buildings to protect the building occupants against COVID-19. There seemed to be a general agreement that HEPA filters could lower the virus particles in the air, but there was not agreement if this would help lower transmission of the virus and infections. There seemed to some non-biological scientists and engineers arguing that it would definitely lower transmission. Others wanted trials and tests. It was simple some said, less virus particles, less transmission. I am engineer, and I found these statements to be rather narrow thinking in consideration of transmission.

I want to explain more fully the flaws I see in the idea that HEPA filters will definitely solve the problem or will greatly help. I need to state first that I am not an HVAC engineer. HVAC by the way, stands for heating, ventilation, and air conditioning. HVAC engineers are the people who design the ventilation systems for buildings. They are also to blame for women always being cold in buildings by the way. The air conditioning design is based on old calculations that involve men in buildings, but I digress. However, my Bachelor’s degree is in chemical engineering, which means I have a good background in fluid flow. Air flowing through a building is fluid flow. Not the kind I normally work in, but fluid flow nonetheless. Also I am not an industrial hygienist. These are the people who figure out how to keep workers safe. I don’t think normal office workers and definitely not school children are their normal scope of work, but they could offer informative thoughts on this.

First, what is HEPA? HEPA stands for high-efficiency particulate air, and HEPA filters are basically really good air filters. Some technical information on them can be found on U.S. EPA’s website. I have really bad allergies, and I have a whole house HEPA filter installed in my house’s HVAC system. There is an initial mesh filter, a giant honeycomb type filter that traps particles then a panel that zaps the air with electricity to kill things. I clean it a couple of times a year. I still sneeze.

For the sake of argument, let’s say that HEPA filters remove all viruses, including COVID-19. For a HEPA filter to work, the virus has to get to the filter. Now we need to think about air flow in buildings, and how the air is going to get to the filter and more importantly how fast the air is going to get to the filter. Most modern non-residential buildings are designed with air ducts and other infrastructure (water and waste pipes, electrical cords, network cords, etc.) overhead in the space between floor above and the drop down ceiling with somewhat ugly acoustical tile. Think of all those movies and tv shows where a character goes into the ceiling and crawls around in the HVAC duct work to get to wherever to save someone or steal a jewel. Thus, in general, all the duct work is overhead, and so the inlet vents, the vents by which the air flows into a room, and the return vents, the vents by which the air leaves the room area, are all overhead. When air leaves the room, it flows back to mechanical works that cool or heat the air. This is where filters, HEPA or not, generally are. The air then goes to a blower which sends it back to the building and its occupants. In a house, the inlet vents are generally in the ceiling or the floor (in my house they are in both depending on the room), and the return vents are often in walls or ceilings. The vent where you place the air filter is the return vent. Thus in most houses, you filter the air after it leaves the room and before sending it to the mechanical works for heating or cooling.

That is the basics of building ventilation. Consider a classroom. Consider if ten children and one teacher are in a classroom, and one child is infected and coughs. Consider the air flow in the average classroom. When the child coughs, the aerosols, droplets, virus, spread out from the child. Unless the HVAC system is pulling the air up and out of the classroom continuously with really good suction, the virus can still easily spread to nearby people. Also, I want to emphasize the word “up” in my previous sentence. It depends on where exactly you are in the room as to the actual direction of airflow. In the office building I normally work in, my cubicle is directly beneath an inlet vent. I know this because I can look up and see it, and because I am always freezing, and because I can hear it when the air blower turns on. Air blows down onto me then outward to the side then pulled up a couple of yards away where the return vent is. I have not mapped out the exact airflow in the building, but you can feel it and make guess based on where the inlet and return vents are. In the vast majority of buildings, you do not feel a breeze. The air is not flowing at a high enough rate for paper to fly away. If paper is not flying away, the virus is probably not either. In my two-story house, there are two return vents, both in the halls. Air flows into the bedrooms, living rooms, etc. into the hall. If two people are in the living room, and one coughs, the cough is going to go out from the person and potentially right by the other person before it ever flows to the return vent. Also, like most houses, my air blower is not on continuously. The air is not always flowing. The same for office buildings. Buildings are designed differently, but I can definitely hear it when the air kicks on, which means it is not always on. If the air blower is not on, the air is not flowing, and virus, particles, etc. are not being pulled out of the space.

In graduate school, I worked in a brand new laboratory building. It literally opened the second year I was there. There was a common area with places to sit, talk, and eat and passages to the adjoining buildings. Off of the common area, where two halls that led to the laboratories. The building was designed for negative pressure. Air flowed from the common area to the halls then to the laboratories. It was perceptible. The doors to the halls, which required a card to open and swung open into the halls, would pull in because of the pressure they were under. You had to physically push the entry door back into place or an alarm would go off. The exit door, which swung open into the common area, would slam shut from the pressure. [Whether or not the negative pressure was too high is debatable.] The building was designed this way so that the volatile chemicals and infectious agents that we worked with in the laboratories would not get into the common areas and expose people. In the laboratories themselves, there were other precautions to protect people inside.

Normal office buildings and schools are not designed this way. They are not designed to be under continuous negative pressure. They not designed to be continuously pulling air away from the occupants. To a certain degree, they are designed to push air onto the occupants. If one person coughs, depending on where they are in the room and the air flow at the time, I would argue that the ventilation may help push the cough droplets from one person to another.

HEPA filters might be able to help solve the COVID-19 problem, but we need studies to show that they can. HVAC engineers and industrial hygienists would need be part of the solution and consider the design of buildings. Independent of COVID-19, HEPA filters are not a bad idea. However, they require more energy to use. Also, consider the time and expense of installing HEPA filters in all the buildings. You cannot just stick one into the system if the system is not designed for it. If it will solve the problem, most of us would say it is worth it, but it is not a problem that can be solved in a day or a week.

If I got anything wrong above, I welcome HVAC experts or filtration experts commenting below.

Edited to add: Someone who read my post stated that portable HEPA filters is what they are suggesting, not whole system filters. My argument remains the same. Assuming they mean one portable HEPA filter per classroom, if the filter is right next to the sick child, it might work. However one of the problems with COVID-19, is you don’t necessarily know who is sick. If the sick person coughs on the other side of the room as the HEPA filter, the portable filter, is going to pull the droplets from the cough across the room to the filter, potentially right by other people. It depends on how fast it pulls the droplets as to if another person would have time to breathe in the droplets, or for the droplets to land on their face. You really need studies to see if this would be effective.

Comet NEOWISE

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Last Thursday after seeing so many fantastic photos of Comet NEOWISE, I made the last minute decision to head to the mountains to try to get some photos for myself. I went to Shenandoah National Park to take photos along Skyline Drive where I could get away from most light pollution and also get a clear horizon view. I also spent two night playing with all the different settings on my extremely high-tech and complicated camera. Even with the owner’s manual, I still was playing around with it. I did finally get a few photos with which I am happy. However, there are still some things I am trying to figure out in terms of how to get photos like others get. Without further ado, here are my photos.

Comet NEOWISE at 10 p.m. as it was finally becoming visible.
Zoomed in photo of Comet NEOWISE
Comet NEOWISE above the Shenandoah Mountains
Comet NEOWISE above the Shenandoah Mountains. The Big Dipper is visible and somewhat identifiable above the comet.
Bonus photo of the Milky Way while I was waiting for clouds to pass to get another photo of Comet NEOWISE. A car passed while the shutter was open (30 sec), and the car headlights lit the trees to make an interesting contrast.

PPE Basics

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People are scared by COVID-19. This is understandable. Some people have started wearing personal protective equipment (PPE), mainly masks and gloves, although some are going for bonus points PPE like protective overalls, because they think the PPE will help protect them from COVID-19. It may, but it may not. I thought I might present just a few basics points for people who don’t normally wear to consider about wearing PPE.

What do I know about PPE you may ask. I am engineer and scientist. I have worn PPE in the field when taking environmental and industrial hygiene samples including soil, groundwater, urine, blood, air samples, and more. To earn my Ph.D., I worked in a lab that handled both chemical and biological samples. That is, one day I might have been handling urine or blood and needed to protect myself from pathogens, and another day I might have been handling chemical samples (or more likely part of a biological sample that had been placed into a chemical for processing) and needed to protect myself from chemical hazards. I am also HAZWOPER certified, and as part of the training, you have to dress in Level A and Level B PPE.

The most basic thing you need to know about PPE is first that PPE is essentially anything you wear that protects you from a hazard. In some places, jeans and long sleeves are PPE because they cover your skin from minor hazards. Steel-toed, leather boots are PPE that I have worn on a frequent basis when in the field as they protect my feet from many physical hazards including in at least one location I was working, rattlesnakes. [Not a hazard I was expecting on that site inspection, but, well, Texas.]

The second most basic thing you need to know about PPE is that it is not magical. PPE has to be worn correctly, and the correct PPE must be worn. For example, not all gloves protect against all hazards. In most of my work, I have worn nitrile gloves. Nitrile tent to be preferred over latex. The minor reason is potential latex allergy. However the main reason is that nitrile protects against more chemicals than latex. For most of my work, it is chemicals for which I need to protect myself. Most gardening gloves will protect you against some physical hazards like prickly vines, but they will not in general protect you against chemicals like pesticides you might be applying.

On the subject of gloves, gloves do not kill bacteria or viruses. If you are worried about viruses getting on your hands because you are touching a grocery cart for example, and so you decide to wear nitrile gloves, if you dispose of the gloves after touching the grocery cart and don’t touch anything else, then gloves may have protected you. However, if after touching the grocery cart with the gloves, you then touch your phone or your face with the gloves, then the gloves have done you no good. You have just transferred any viruses from the grocery cart to your gloves to your phone or face, just as efficiently as if you had not worn gloves. A week ago, I went to Costco and went first to the bathroom. When I was washing my hands, I noticed a woman washing her hands while wearing latex gloves. I simply don’t want to know what else she touched with the gloves before doing this or after.

A final note about gloves, there is a definite technique to how to remove them. The goal is to remove them without touching the outside of them. There may possible be another way, but the best way I have found to do it, is place one gloved finger on the outside of the other hand’s glove, near the wrist and carefully pull that other hand’s glove off, sort of rolling it off. Then with the now glove free hand, place your ungloved thumb under the other glove near the wrist and pull that glove off. Easier to show than explain.

Masks and respirators are designed for different types of protection, and it is critical that they be worn properly and for the correct use. Surgical masks are really more to the protect the patient from the surgeon sneezing or coughing on them than to protect the surgeon from the patient. Surgical masks can protect the wearer from splashes or larger droplets or to a certain extent large particles, but that is about it. Surgical masks do not provide even a decent seal around the face, so they do not protect from airborne viruses, bacteria, chemicals, or even small particles. If you don’t believe me, believe the FDA.

The now popular N95 masks can protect against some particles, viruses, and some other things if worn correctly. First, it is important to consult the manufacture’s information as to what they are designed to do and not to do. Second, it is critical that the wearer has a good seal. What does that mean? It means the edges of the masks must fit snugly against the skin for the entire perimeter of the mask. Men, you have to be clean shaven. Even an evening stubble will prevent the seal. N95 masks have a piece of metal that goes over the nose. That metal needs to be adjusted to get a good seal over the nose. Both elastic bands for the mask must be used to increase the fitness of the seal. Finally, masks get saturated. They can only be worn for a certain period of time before whatever you are breathing in breakthrough the mask.

I can’t emphasize enough how critical seals are. When I was graduate school, for the field work I was doing, I needed to be able to use a half-face respirator. That required me to first get medical clearance to wear the respirator. Second, I had to be fit-tested for the specific respirator I was going to wear. Different manufacturers make different size masks, and they don’t generally agree with each other. Hence I was fit-tested to wear a specific manufacture’s specific sized mask, and that was the one I wore throughout my field work.

Finally with respirators and masks also, the manufacture will state what the respirator or mask is designed to protect you from. If you go to a hardware store and look at respirators, you will notice that some respirators are for lead, some for particulates, some VOCs, and some will do a combination. A mask to protect from VOCs and PM10 is common. If you are going to work with VOCs, and you get one that is only for PM10, you will not be protected at all. Cartridges for respirators have to be changed frequently. Every two weeks is a common changeout time.

Those are the basics. There is really a lot more to understand about PPE, but those of the initial basic critical points to understand if you are thinking about wearing PPE to protect you from a virus or other hazards.