science

NOREM

NOREM is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand NOREM rather than just read about it. In short: NOREM is a hardfacing material developed by the Electric Power Research Institute to deal with radiation safety issues associated with the use of cobalt alloys in nuclear power station coolant systems (see stellite for a discussion of the problem). It is a solid-solution strengthened austenitic matrix with a continuous network of eutectic and non-eutectic carbides at the grain boundaries.

Key takeaways

NOREM belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect NOREM to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NOREM from memory before moving on to harder problems.

Reference excerpt

NOREM is a hardfacing material developed by the Electric Power Research Institute to deal with radiation safety issues associated with the use of cobalt alloys in nuclear power station coolant systems (see stellite for a discussion of the problem). It is a solid-solution strengthened austenitic matrix with a continuous network of eutectic and non-eutectic carbides at the grain boundaries. It is intended to be deposited by various welding processes.

Characteristics There are eight variants of NOREM currently available, depending on application and designated 02, 02A, 03A, 03B, 04A, 04B, 05A, 05B. A typical elemental composition is 60% iron, 25% chromium, 4.5% manganese, 4.0% nickel, 3.3% silicon, 2.0% molybdenum, 1.2% carbon. Earlier compositions included either significantly more manganese (12% in alloy 04) or significantly more nickel (8% in alloy M2). These are extremely hard alloys. NOREM 02 is ten times as resistant as 308 stainless steel to cavitation erosion. They are essentially corrosion-immune under the conditions inside CANDU reactors and erode at about 200 micrograms per square centimetre per year under pressurized water reactor conditions. Due to the high hardness, the strength is relatively low: approximately 120 ksi (830 MPa) yield strength and it fails at 0.6% elongation.

Use in power plants The first use of NOREM was as replacement discs in three Chemical Volume Control System isolation valves at Consolidated Edison's Indian Point unit 2. It is now used in about 800 valves installed by about 30 utility companies. There has been one case of a NOREM valve disc being found damaged, at the Callaway Nuclear Generating Station, though it seems the valve was not being used in an appropriate application. Given the high cavitation resistance, NOREM has been tested for hydroelectric applications; it seems not to be as impressively cavitation-resistant in the field as in the lab, though only one layer of the material was used in the test, and the Electric Power Research Institute recommends at least two.

References Performance of NOREM Hardfacing Alloys

Further reading Stainless steels By Joseph R. Davis

Worked examples

Example 1 — a first encounter with NOREM

Start with the simplest possible case. Write down what NOREM claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to NOREM before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about NOREM ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of NOREM

In research: NOREM appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses NOREM in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: NOREM is common in secondary-school and first-year university syllabi. It links to neighbouring topics Welding, so understanding it makes those chapters shorter.
In everyday life: Look for NOREM outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study NOREM in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NOREM means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain NOREM out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NOREM in simple terms?

Why does NOREM matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study NOREM?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on NOREM.