This Explains Why You Can’t Break Your Lug Nuts Loose After Going To The Tire Shop…..

They must use this same method.


lug nuts

It’s not really possible to torque down a set of bolts onto the top of a nuclear reactor assembly by conventional means, so instead, the head assembly is heated up while the bolt is cooled with liquid nitrogen, correspondingly expanding the reactor top and shrinking the bolts. They are then torqued into place and allowed to thermalize, resulting in something like 1/4 million foot-pounds of torque holding the assembly together.

10 thoughts on “This Explains Why You Can’t Break Your Lug Nuts Loose After Going To The Tire Shop…..

  1. Sorry, but the visual is broken. That is a TRIGA reactor pulsing – maybe setup to oscillate but appears to just be a pulse played in a loop. It is in an open pool filled with _very_ clean water you can see down thru – hence the pretty pictures.

    The description is backwards, and not unusual for large, high stress bolted joints. Turbine shells (the big steam and gas ones that make all the electricity) have bolts with hollow cores that permit heating them to elongate and permit tensioning and detensioning. The bolts (unless more modern tools are available) are ‘slugged’ with a wrench you stand on and whack with a sledgehammer. While hot.

    Reactor heads are usually (not always) tensioned and detensioned with machines made for that specific application. Some remove all bolts in one action – others a third or half. All bolts are cleaned, inspected (UT, etc.), and readied for re-use or replaced as needed. PWRs operate at about 2250 psia – hence the big heads and bolt loads. Spread 2250 over a disk 30 feet across and there is a little up-force on the lid when the system is pressurized. Allowed operatoinal leakage is basically zero (a little is permitted, but generally NOT from the head/vessel joint – which is usually monitored continuously.

    Big F’ing machines – big F’ing loads, big F’ing tools. That TRIGA in the picture is a toy in comparison (the holes and fuel you can see are about 1.5 inches across.)

    Formerly licensed operator of a TRIGA, long time ‘big plant’ engineer.

    Liked by 2 people

    • I’m obviously no Nuclear Engineer. I appreciate you setting that straight. I figured it was bogus when it said that they cryogenically cooled the bolts anyway.
      I work around liquid argon. I also know what cooling some metals down to that temperature does. It makes it as brittle as glass. Every valve and piece of pipe they use for that at work is thick walled stainless steel.
      I just thought it was a cool meme and it gave me a chance to be a smart ass.
      I know I have broken high dollar tools trying to break loose lug nuts that got hammered on with an impact gun before.


  2. Owning a repair shop…… salt. Rust. You are cheap ..employees are paid shit. your wheels barley made it back on..Shut the fuck up.


  3. Ho-Hum. Refuelled a reactor in shipyard. So droll and boring. Nothing to see. Except those torque wrenches were calibrated 8 foot long monsters.
    While defuelled us nukes had a to stand watch on a discharge catch tank in the drydock in the middle of New Hampshire winter. Some sympathy tears would be appreciated.


  4. Um, that torque reading is actually a measure of the friction between the bolt and nut threads and is loosely related as a function of tension. For actual tension measure in a bolt to get the correct clamp load one has to use bolt stretch gauges. Metals have a relatively linear relation ship between strain and stress in their elastic region of the stress strain curve. (see Hooke’s Law) It’s possible to calculate the clamp load knowing the bolt material, manufacturing technique and the overall stretch. You typically see this technique in big money racing engines for the rod bolts.

    BSME, Minnesota, last century.
    Best primer on Material Science and gut level engineering are in Carrol Smiths’ books.


  5. I used to do fieldwork on some compressors at a dealership. The mechanics
    insisted on 175 PSI or better. Almost all air tools are rated at 90-100 PSI.
    This was before the advent of 1/2″ 750 foot-pound super duty impact wrenches.
    No matter where I worked, there was always some fucking gorilla who never
    understood the concept of torque.

    The worst case I ever encountered was a paper mill machine screen. Some
    total dipshit pounded down the bolts on a tapered bore pulley with a super
    duty impact. The installation instructions for tapered bore pulley/bushings
    states do not use impact tools. Torque to normal values with hand tools.
    do not use Millwright KY-Gel (AKA stud butter, AKA Never Seeze.)

    How the moron managed this without cracking the pulley hub was beyond
    me! We ended up using a hot wrench to cut the pulley spokes off near the
    hub in order to lift the machine out of the base.


  6. nuclear plant maintenance was a fun gig. for real suffering in a maintenance department, a plant that handles paper/wood pulp/fiber of any sort is where you want to be from. paper can turn hardened tool steel cutters into something duller than wet leather. paper dust can destroy the tightest sealed component of moving machinery is less time than it takes to order a new part. paper dust has destroyed the ability of electrical contacts to function at anything less than 120vac. moist paper fiber can short out the finest computer control systems and play havoc with automatic controls. 24vdc controls switches fail regularly from dust contamination. laser and photo switches fail because the smallest bit of fiber gets on the lenses and disturbs the calibration. gears, bearings, cooling systems, lubricants, measuring systems, steam plants, valves, air compressors, hydraulic systems. a filter has never been devised that could stop wood pulp fibers from entering the protected systems.
    but, cheater bars on a wrench can undo all the good you have ever done in your life.
    did I mention how pleased I am to now be retired?


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