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Tag Archives: Nuclear

Melting an Industry Frozen in Time

MH1Asimulator

During the Nuclear Power boom of the late 1960’s and 70’s, industries rushed in to design, fabricate and supply safety related components under a 10CFR50 Appendix B Quality Assurance Program. During this period, the technology life cycle could be 20+ years in which these items would be supported and replacement parts to maintain them available. As things slowed in the mid-80’s and throughout the 90’s, many equipment manufacturers began to focus their efforts on providing products for larger commercial markets where they had the freedom to innovate instead of being bound by the 10CFR50.

Maintaining the nuclear fleet with new technology and where existing equipment is no longer supported is a challenge in an industry in which plants were originally designed and licensed 30+ years ago and are now being granted 20 year life extensions.

To illustrate this point, nuclear plants used to record data on strip chart recorders which had scrolls of paper and pens capturing a number of things like process temperatures, flows, pressure, etc. As these technologies have innovated into digital format the parts and supports of the strip chart recorders are no longer available. The nuclear plants had no choice but to accept and use the new technology.

Working with partners like Yokogawa Corporation of America, NTS qualified a line of DXAdvanced Digital Recorders and Data Acquisition (DAQ) for use in safety related nuclear applications. The current models of these recorders is the DX364, DX1000N, DX2000 series and MW100 DAQ which can monitor and record up to 4, 12, 48 or 500 channels of data respectively. NTS performed equipment qualification testing under our Quality assurance Program 10 CFR 50 Appendix B (similar to NQA-1) of these items including:

  • Environmental Testing/Analysis per IEEE Std 323
  • Seismic Testing per IEEE Std 344,
  • EMI/RFI Testing to US NRC Regulatory Guide, 1.180, Rev 1 (Guideline of Mil Std 461E)
  • Firmware Validation and Verification to IEEE Std 7-4.3.2

NTS then performs commercial grade dedication activities and supplies these items to our nuclear clients as “basic components”, or being safety related.

In addition to these models which have different sizes and capabilities, NTS has also qualified a variety of adapter plates so that when the old item is removed from the control board, there is a structural plate which will envelope the vacant panel cutout. This will house the recorder which is smaller, more compact, and lighter in weight than the item it replaces.

NTS has worked with several utilities in customizing solutions which will minimize the impact on any plant design changes. These modifications have included the design, fabrication, qualification and supply of plant specific custom cases so that use of the existing plant infrastructure is maximized.

Additional examples of equipment obsolesce solutions that NTS has qualified for nuclear safety related applications are: Yokogawa YS-1700 Digital Controllers, Diesel Monitoring System, 812 Timing Relays, Flasher Relay, and Motors.

As technology changes and more and more items become obsolete, NTS will continue to support our clients in qualifying new technology and help maintain the nuclear fleet so it can produce safe, reliable and no carbon emission electricity.

NTS LOCA: An Accident Gone as Planned

ThreeMileIsland

Three Mile Island power plant

On March 28th 1979, “TMI-2 Reactor Destroyed” was the topic that swept this nation. After having been online only 13 months, Unit 2 in the Three Mile Island nuclear power plant had a partial core meltdown due to a fault that initiated in the secondary side of the plant which ultimately lead to a Coolant System Failure. This was “The Accident” that went beyond the designed second tier fault tree to reach the other safety systems per their design.

The Nuclear Power Plant Safety Protocol has multiple planned accident scenarios (fault trees) that they have designed into their safety programs. The major accidents designed into the Emergency Core Cooling System fall into the following two categories:

  1. Criticality Accidents, Example: Chernobyl (1986) and Fukushima Daiichi (2011)
  2. Loss of Coolant Accident, Example: Three Mile Island (1979)

This Loss of Coolant Accident environment is simulated at the NTS Huntsville Facility to ensure that the surrounding equipment survives the necessary time span required for the equipment to perform its designed safety functions and ensure cooling of the reactor core. It is theorized that during a LOCA event, the initial 5 minutes are the worst condition for equipment in regards to Temperature, Humidity and Pressure, reaching maximum temperature within 10 seconds and the most critical for plant safety.

NTS has been performing these accidents runs for the last 35 years and currently the NTS Huntsville system is used to provide harsh environment needed for testing for the components that will be subjected to a High Energy Line Break (HELB) or Main Steam Line Break (MSLB). The purpose of these tests, which is conducted in accordance with IEEE Standard 323 are to subject the Equipment Under Test (EUT) to a rapid rise in temperature and pressure that may be experienced inside a Nuclear Power Plant Containment Structure or Main Steam line area should there be a catastrophic line rupture. The objective is to reach temperature of over 375°F and pressures as much as 70 PSI in less than 10 seconds then hold a lower temperature and pressure for a period of up 30 to 60 plus days.

The boiler system is designed for 350 PSIG, 800°F of superheated steam with a designed steam capacity of 11,000 Lbs/Hr. There are two test autoclaves which the (EUT) can be placed in; one rated at 300 PSIG, and the other 150 PSIG. The system also has the capacity to mimic the Core Spray System inside of the containment structure to quench the pressure and steam by providing a spray of a buffered boric acid solution. The LOCA system is monitored and test data is collected on a Custom Integrated Control and Data Recording System developed by our NTS Albuquerque Operation.

Other industries who may utilize this super-heated steam testing are: Cable Mfg, Valve & Actuator Mfg, Relay Mfg, Military Std 810 testing facilities, I&C Instrumentation Mfg, RTD/Thermistor Mfg, Pressure Transducer Mfg and Enclosures Mfg. For more information on our LOCA testing services you can contact Huntsville at 256-837-4411 or visit the webpage for more information.