Category Archives: Engineering

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)

Stair Pulley System

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Surgery for scoliosis was two months ago now, and I am still recovering. My ability to walk is improving slowly as my body adjusts to the new spinal arrangement. I have a limp that is going to take time to fix. I can climb and descend stairs, but I have to hold onto the railing with one hand, and it is really better if my other hand is at least touching the other side. The main part of my house is on the second floor, so I have had to figure out how to get things up and down the stairs if I want to live on my own.

There are a couple of solutions, but I am engineer, so naturally I installed a small pulley system to transport items up and down the stairs. I think it is the most efficient solution. I bought a small pulley with accompany hook and rope, and I installed it on the railing overlooking the stairs. My stairs have a landing at the halfway point where they change directions, so that made the pulley system really easy to install and allow for a straight path for items to ascend and descend.

Note that my cats oversee all operations of the pulley.

Pulley system installed on stair railing

Pulley used

Groceries loaded onto hook to lift to second floor

Groceries pulled to the second floor

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

Powerhouse Arts

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Powerhouse Arts is a new arts and fabrication studio and rental venue housed in a renovated power station in Brooklyn, New York, and they hosted an open house today through Open House New York.The building has been completed renovated, but they have left some of the graffiti on the walls from when the place was essentially abandoned, and squatters lived there. The facility now houses several different art studio areas like a ceramics area and print shop. It also has huge spaces that can be rented. The facility is right on the Gowanus Canal, and it has wonderful views of Brooklyn and Manhattan.

Powerhouse Arts located in an old power station

Former steam production area

Downtown Manhattan and the Gowanus Canal can be seen

Former turbine hall

Former turbine hall

Former turbine hall

Newly commissioned artwork in the Grand Hall

Graffitti in entrance hall

Historic Richmond Town, Staten Island

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Last week, I went for a guided walk with NYC H2O of historic Richmond Town, Staten Island to hear about the history there, in particular how the water affected the history. Historic Richmond Town is a neat little area as it is a park of historic buildings. If I read the information correctly, some of them were moved there to be part of the preservation area. There is a mill there that operated off the creek that runs by the area. Nearby and also part of our walk is Brookfield Park, which is a former landfill. From an environmental engineering perspective, it is nice to see what the landfill has become. Although it is not clear if remediation is ongoing, as the landfill was rather old, so it is not clear what engineering, if any, went into it.

Third County Courthouse

Former County Clerk’s and Surrogate’s Office

Tin Shop

Historic Richmond Town

Old Mill

St. Andrew’s Church

Brookfield Park

Brookfield Park

Bridge Walk

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I spent today doing more exploring of New River Gorge National Park, but I started the day by walking across a bridge. The walk across the bridge was under the road deck, which is not something a person normally gets to do. Bridge Walk lets you do just that. The New River Gorge Bridge is beautiful with a wonderful design, and walking under the bridge allowed me better appreciate and to take photos of the structure. Walking on the catwalk also allows for photos of the stunning scenery. It was a nice, leisurely walk that just happens to be, at the highest point, 876 feet above the ground, by walking on a two feet wide catwalk while attached the longest continuous safety line in the world.

Looking up to Bridge Walk from Fayette Station Road

View to the west

Looking down at the piers

View to the east

Looking down at the arch

Looking down at the arch

View to the west

Looking down at the arch

At apex of arch

Looking down at the arch

View to the west

Looking down the catwalk

Nuttallburg

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I started exploring New River Gorge National Park today. It is second on my list of things to see in West Virginia after the capitol. The park is really spread out, and there are lots of areas to explore. I did some hiking in the Nuttallburg area today because it features the remains of a coal mining operation, and I love ruins. I hiked from the top to the headhouse. I was originally going to hike down along the trail that somewhat follows the conveyor, but I met some people at the headhouse, who had just hiked up the that trail, and they said do not do it. It is a really difficult trail, and while the park material said as much, somehow their exhausted faces persuaded me more. I then drove to area near the river where the lower part of the mining operation was and hiked around there a little. The area trails are really neat because you can essentially follow the mining operation from the mine entrance to where the coal would have been loaded onto trains.

While the mining operation started in the mine, obviously, the first part you can see is the mine entrance. As I stood in front of the mine, I could feel the air coming out was probably 10 or 20 degrees colder.

Mine Entrance

The coal cars then went to the headhouse where the coal was dumped and loaded onto the conveyor, which brought the coal all the way down the slope to be transferred to trains.

Headhouse where coal was dumped out of the cars from the mine and onto the conveyor. In the lower right, you can see the start of the conveyor.

Inside the headhouse where the coal cars came in

The conveyor was essentially a really long conveyor belt, and it was kind of awesome to stand beneath it.

Conveyor that brought coal from headhouse to tipple

The conveyor ended at the tipple. The tall structure seen on the right was a storage silo for the coal.

Conveyor entering the tipple

Conveyor entering the tipple

The tipple sat on top of train tracks, and the coal was transferred to the trains there.

Tipple where coal was transferred to trains

Under the tipple, standing on the old train tracks where coal was transferred

There are also some remains of coke ovens. These are considered to be the earliest remains of coal operations. Originally the coal converted to coke there.

Coke Ovens

JQ Dickinson Salt-Works

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I visited JQ Dickinson Salt-Works, a small, salt-harvesting facility today, and it was fascinating. I love factory tours, but I don’t think the term factory applies to this place, and it would almost be derogatory to call the salt works a factory. In any event, the process was fascinating, and I am somewhat in awe of how low-tech it is, yet I am amazed how they can produce so much salt. My guide said they will produce about 16,000 pounds of salt this year. There used to be springs in the area that Native Americans knew about as they knew that animals liked to lick the salt from the springs. Salt was produced commercially from the springs when white settlers moved in to the area, but then production ended in the twentieth century. The operation was resumed more recently, and the current well was installed in 2013.

The start of the process is somewhat anticlimactic. The process starts with groundwater that is pumped from an aquifer that is 350 feet deep and contains water from an ancient ocean. The anticlimactic part is that the well is below ground (obviously), and so all you see from the surface is a tripod of sorts marking off the location.

Groundwater well that eventually produces salt

The groundwater is first pumped into storage tanks to allow the iron to settle out from the water.

Groundwater storage to separate iron from water

They have sample jars that show what the water looks like when mixed (right) and then once the iron has settled and comes out of solution (left). My guide said they try to keep the process as environmentally friendly as possible and allow little to nothing go to waste. The iron that settles out is eventually sold for wood staining or for pottery glazes.

Sample jars showing iron separating from groundwater

After the iron settles out, the water is pumped to one of three greenhouses to concentrate in shallow pools in black-lined tables.

Greenhouse for concentrating groundwater to brine

I forgot to ask my guide what the starting salinity of the groundwater is, but in these first greenhouses, it sits for about 24 hours until it reaches a salinity of 15%. In the shallow pools, I could see a few fine salt crystals settling out.

Greenhouse for concentrating groundwater to brine

The concentrated water or brine is then pumped to another storage tank and then into another greenhouse. In this greenhouse, the salinity is raised to 25%. This is where large salt crystals are formed. One thing I got confused about is that my guide said the salt was now 25% salinity, but they were clearly salt crystals. Visually it didn’t look like 75% water and 25% salt. I am not sure if I understood correctly what is meant by salinity or if I misunderstood her, or if I am just missing a detail. In any event, the salt was quite pretty.

Salt crystalizing

One of the tables had been cleared of the concentrating salt, and there were buckets of salt crystals ready for final processing.

Bucket of salt crystals ready to be dried

The salt is then moved to another room where it is dried. After that, a person inspects the salt and removes any impurities with tweezers. The women who were working admitted that it is a really tedious job. I would need a headlamp and magnifying glasses to do the task.

Cleaning salt by hand

The salt is then ready to be sold. They sell it in three crystal sizes (from finest to coarsest): popcorn, finishing, and grinding. They also mix it with spices, most or all of which are grown locally, to sell as spice salt mixes. The liquid that is left over once the salt settles out is also sold as nigari. Nigari is used to make tofu and cheese, and some people take it as supplement as it is full of minerals. This is part of what my guide said is their goal to not let anything go to waste. Until today, I had never even heard the word nigari, so yet another thing I learned today.

Samples of salt products sold. The red salt is not sold, but it is a very red in color salt that they have to show people what the salt would look like if they did not allow the iron to settle out first. At the bottom of the photo are three giant halite crystals to show how large the salt can grow.

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.