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Division Spotlight
Nuclear Installations Safety
Devoted specifically to the safety of nuclear installations and the health and safety of the public, this division seeks a better understanding of the role of safety in the design, construction and operation of nuclear installation facilities. The division also promotes engineering and scientific technology advancement associated with the safety of such facilities.
Meeting Spotlight
Utility Working Conference and Vendor Technology Expo (UWC 2024)
August 4–7, 2024
Marco Island, FL|JW Marriott Marco Island
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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Latest News
Four million nuclear jobs by 2050: Who will do them?
Industry leaders from around the globe met this month to discuss the talent development that will be necessary for the long-term success of the nuclear industry.
The International Conference on Nuclear Knowledge Management and Human Resources Development, hosted by the International Atomic Energy Agency, was held in Vienna earlier this month. Discussed there was the agency’s forecast for nuclear capacity to more than double—or hopefully triple—by 2050 and the requirement of more than four million professionals to support the industry.
R. Muralidharan, V. K. Chexal
Nuclear Technology | Volume 78 | Number 1 | July 1987 | Pages 13-23
Technical Paper | Nuclear Safety | doi.org/10.13182/NT87-A34004
Articles are hosted by Taylor and Francis Online.
The emergency core cooling systems (ECCSs) at a reactor site have a dual power source for their assured operation if and when needed. The normal power source is the off-site ac power. In the unlikely event of loss of all off-site power, emergency diesel generators (DGs) are the backup ac source. Thus, there is an incentive to ensure that the reliability of DGs at operating plants is maintained at an acceptable level. A potential contributor to observed diesel degradation is the fast start and loading interval (∼10 s) demanded of the emergency DGs. Such fast start intervals result from the performance required of the ECCS to meet the U.S. Nuclear Regulatory Commission (NRC) acceptance criteria for a hypothetical large-break loss-of-coolant accident (LOCA) (design basis accident) concurrent with a loss of off-site power. The guidelines established by the NRC for the ECCS performance evaluation, which are stated in Appendix K of 10CFR50, have several built-in arbitrary conservatisms. Recently, the NRC outlined in SECY-83-472 a new approach for performing ECCS analysis and has given approval to General Electric to use this new approach in their SAFER/GESTR LOCA analysis computer code. The sensitivity of peak cladding temperature (PCT) is determined using the new realistic LOCA analysis approach for various DG start durations. A quantitative assessment of the various diesel start durations using NRC licensing assumptions was made to determine the impact on the PCT. The results for a boiling water reactor (BWR/6) show that when using licensing assumptions and the SAFER/GESTR code, the PCT that is determined during a design basis LOCA for the present 10-s DG start criteria is ∼593°C. This is far below the prescribed limit of 1204.4°C. The results also show that the PCT varies only a small amount with diesel start times of 10 to 30 s. Thus, the diesel start time for the class of reactors analyzed in this study could be changed from 10 to 30 s without the loss of any LOCA safety margin. The results further show that for an 871.1°C PCT, which is the current NRC-approved SAFER application PCT limit, the DG start time can be 70 s (compared to the present specified 10 s). The DG start time could be increased to 118 s when and if, in the future, the SAFER code is qualified to a PCT limit of 1204.4°C for licensing calculations. This work is of interest to nuclear utilities as a means of increasing operational flexibility and to help improve diesel reliability.