July-August 2018 NPJ

Nuclear Plant Journal, July-August 2018 NuclearPlantJournal.com 29 much longer than conventional PWRs. This process delay and the response time of the RTDs must be known at all potential operating flows in order to verify that the sensors can provide timely measurements for plant control and safety. NuScale Power has already selected RTDs for hot leg, cold leg, and other safety-related temperature measurements as shown in Figure 3. Note that there are a number of redundant thermowell-mounted RTDs on both sides of the reactor, on the top for hot leg temperature measurement and on the bottom for cold leg temperature measurement. As a part of the DOE project, AMS will generate RTD response time versus RCS flow characterizations to establish sensitivity to flow and determine maximum in-service response time at minimum RCS flow rates. This laboratory data is needed to help extrapolate RTD response time testing results from one flow condition to another. Measurement of Air and SteamTemperature in NuScale Reactor In addition to the RCS, some RTDs in the NPM will be used to measure temperature in steam or air processes (e.g. Main Steam (MS) temperature and Under-the-Bioshield temperature). As the dynamic performance of an RTD depends, in part, on the surrounding medium, it must be demonstrated first through laboratory measurements and confirmed subsequently via on-site testing that the selected RTDs can meet the plant technical specification for response time in steam or air at the in- service flow rates. This may be a challenge, particularly for temperature measurements in air, because the response time of a typical nuclear grade RTD can be several seconds in flowing water but an order of magnitude greater when in air flowing at the same velocity. Therefore, RTD prototypes will be tested at representative process conditions and guidance will be provided to the manufacturer as necessary to ensure that the final design of the RTDs will satisfy the plant technical specifications. Contact: Alex Hashemian, AMS, telephone: (865) 691-1756, email: Alex@ams-corp.com Nuclear Industry’s Best Protective Apparel Reduce Reuse Recycle Compare costs www.UniTechUS.com/PE Call 1-800-344-3824 www.UniTechUS.com Save up to 50% with ProTech Plus ® launderable coveralls and CoolTech ® Scrubs – toss the disposables Choose our ONE Program with low cost-per-use charge for apparel, accessories, Mobile Safety Store – scrap inventory costs ProTech Plus balances protection, comfort, cost – best for worker, company & environment CUT COSTS!