One Two Three One Two Three
Azalee Rowling
The National Research Council's (NRC) Framework describes a vision of what it means to be proficient in science; it rests on a view of science as both a body of knowledge and an evidence-based, model and theory building enterprise that continually extends, refines, and revises knowledge. It presents three dimensions that will be combined to form each standard:
Although engineering design is similar to scientific inquiry there are significant differences. For example, scientific inquiry involves the formulation of a question that can be answered through investigation, while engineering design involves the formulation of a problem that can be solved through design. Strengthening the engineering aspects of the Next Generation Science Standards will clarify for students the relevance of science, technology, engineering and mathematics (the four STEM fields) to everyday life.
The NRC cross-cutting concepts have application across all domains of science. As such they are a way of linking the different domains of science. They include: Patterns, similarity, and diversity; Cause and effect; Scale, proportion and quantity; Systems and system models; Energy and matter; Form and function; Stability and change. The Framework also emphasizes that these concepts need to be made explicit for students because they provide an organizational schema for interrelating knowledge from various science fields into a coherent and scientifically-based view of the wor
Disciplinary core ideas have the power to focus K-12 science curriculum, instruction and assessments on the most important aspects of science. To be considered core, the ideas should should meet at least two of the following criteria and ideally all four: Have broad importance across multiple sciences or engineering disciplines or be a key organizing principle of a single discipline; Provide a key tool for understanding or investigating more complex ideas and solving problems; Relate to the interests and life experiences of students or be connected to societal or personal concerns that require scientific or technological knowledge; Be teachable and learnable over multiple grades at increasing levels of depth and sophistication.1 Disciplinary ideas are grouped in four domains: the physical sciences; the l
The leader in boutique fitness, Studio Three encompasses three, elite fitness studios under one roof: Interval, Cycle and Yoga. Tailored to athletes of all skill levels, group classes in each discipline are expertly led by world-class instructors who inspire growth at every stage of your fitness journey. The S3 experience is powered by state-of-the-art technology, enhanced by stunning design and premium amenities, and sealed with an unparalleled community.
June 26, 2024 update: BLM is working with the U.S. Forest Service - Lincoln National Forest to keep the interpretive visitors center open from 9 a.m. - 2 p.m. until July 1. On July 3, we will have a new volunteer site host. The hours will be from 9 a.m. to 3 p.m. Thursdays through Mondays. This does not affect the day operations regarding fee collections for the RV and picnic sites. The site will remain open seven days a week.
The Three Rivers Petroglyphs are outstanding examples of prehistoric Jornada Mogollon rock art. The basaltic ridge rising above the Three Rivers Valley contains over 21,000 petroglyphs, including masks, sunbursts, wildlife, handprints, and geometric designs. The number and concentration of petroglyphs make this one of the largest and most interesting rock art sites in the Southwest. A rugged 0.5-mile trail (Petroglyph Trail) begins at the visitor shelter and links many of the most interesting petroglyphs. Another short trail (Village Trail) begins on the east side of the picnic area and leads to a partially excavated prehistoric village.
The Three Rivers Petroglyph Site is one of the few locations in the Southwest set aside solely because of its rock art. It is also one of the few sites giving visitors such direct access to petroglyphs. The number and concentration of petroglyphs here make it one of the largest and most interesting petroglyphs sites in the Southwest. More than 21,000 glyphs of birds, humans, animals, fish, insects and plants, as well as numerous geometric and abstract designs are scattered over 50 acres of New Mexico's northern Chihuahuan Desert. The petroglyphs at Three Rivers, dating back to between about 200-1450 AD, were created by Jornada Mogollon people who used stone tools to remove the dark patina on the exterior of the rock. A small pithouse is nearby and Sierra Blanca towers above to the east. A detailed petroglyph guide is available at the Three Rivers Petroglyph Site.
A rugged half-mile trail (Petroglyph Trail) begins at the visitor shelter and links many of the most interesting petroglyphs. Another short trail (Village Trail) begins on the east side of the picnic area and leads to the remains of a Mogollon village, whose inhabitants were likely responsible for the petroglyphs. Occupied for about 400 years, the site was partially excavated in 1976. On the village site, there are foundations of three types of prehistoric buildings. A small pueblo ruin is nearby and Sierra Blanca towers above to the east. Just up the road is Three Rivers Campground (closed due to fire damage) and an entry point into the Lincoln National Forest.
The site offers five shelter sites with picnic tables and cooking grills (one is handicap accessible); one group site that has three picnic tables under a shelter and two grills; two RV sites have covered picnic tables and grills and water and electric hookups. Five locations are also established for tent use, within defined boundaries. One of the tent locations is at the handicap accessible site. Restrooms and drinking water are available. Pets are allowed in the campground (on leash), but are not allowed on the trails.
The site is located 17 miles north of Tularosa, NM, and 28 miles south of Carrizozo, NM on U.S. 54. Turn east from U.S. 54 at Three Rivers onto County Road B30 and travel five miles on paved road, following signs.
The Three Mile Island power station is near Harrisburg, Pennsylvania in the USA. It had two pressurized water reactors. TMI-1, a PWR of 880 MWe (819 MWe net) entered service in 1974, and remained one of the best-performing units in the USA until it was shut down in 2019. TMI-2 was of 959 MWe (880 MWe net) and almost brand new at the time of the accident.
The accident to unit 2 happened at 4 am on 28 March 1979 when the reactor was operating at 97% power. It involved a relatively minor malfunction in the secondary cooling circuit which caused the temperature in the primary coolant to rise. This in turn caused the reactor to shut down automatically. Shut down took about one second. At this point a relief valve failed to close, but instrumentation did not reveal the fact, and so much of the primary coolant drained away that the residual decay heat in the reactor core was not removed. The core suffered severe damage as a result.
The operators were unable to diagnose or respond properly to the unplanned automatic shutdown of the reactor. Deficient control room instrumentation and inadequate emergency response training proved to be root causes of the accident.
Within seconds of the shutdown, the pilot-operated relief valve (PORV) on the reactor cooling system opened, as it was supposed to. About 10 seconds later it should have closed. But it remained open, leaking vital reactor coolant water to the reactor coolant drain tank. The operators believed the relief valve had shut because instruments showed them that a "close" signal was sent to the valve. However, they did not have an instrument indicating the valve's actual position.
Responding to the loss of cooling water, high-pressure injection pumps automatically pushed replacement water into the reactor system. As water and steam escaped through the relief valve, cooling water surged into the pressurizer, raising the water level in it. (The pressurizer is a tank which is part of the primary reactor cooling system, maintaining proper pressure in the system. The relief valve is located on the pressurizer. In a PWR like TMI-2, water in the primary cooling system around the core is kept under very high pressure to keep it from boiling.)
Operators responded by reducing the flow of replacement water. Their training told them that the pressurizer water level was the only dependable indication of the amount of cooling water in the system. Because the pressurizer level was increasing, they thought the reactor system was too full of water. Their training told them to do all they could to keep the pressurizer from filling with water. If it filled, they could not control pressure in the cooling system and it might rupture.
Steam then formed in the reactor primary cooling system. Pumping a mixture of steam and water caused the reactor cooling pumps to vibrate. Because the severe vibrations could have damaged the pumps and made them unusable, operators shut down the pumps. This ended forced cooling of the reactor core. (The operators still believed the system was nearly full of water because the pressurizer level remained high.) However, as reactor coolant water boiled away, the reactor's fuel core was uncovered and became even hotter. The fuel rods were damaged and released radioactive material into the cooling water.
At 6:22 am operators closed a block valve between the relief valve and the pressurizer. This action stopped the loss of coolant water through the relief valve. However, superheated steam and gases blocked the flow of water through the core cooling system.
Throughout the morning, operators attempted to force more water into the reactor system to condense steam bubbles that they believed were blocking the flow of cooling water. During the afternoon, operators attempted to decrease the pressure in the reactor system to allow a low pressure cooling system to be used and emergency water supplies to be put into the system.
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