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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Deep Space: The new frontier of radiation controls
In commercial nuclear power, there has always been a deliberate tension between the regulator and the utility owner. The regulator fundamentally exists to protect the worker, and the utility, to make a profit. It is a win-win balance.
From the U.S. nuclear industry has emerged a brilliantly successful occupational nuclear safety record—largely the result of an ALARA (as low as reasonably achievable) process that has driven exposure rates down to what only a decade ago would have been considered unthinkable. In the U.S. nuclear industry, the system has accomplished an excellent, nearly seamless process that succeeds to the benefit of both employee and utility owner.
Hassan S. Basha, Michael P. Manahan, Sr.
Nuclear Technology | Volume 100 | Number 1 | October 1992 | Pages 79-96
Technical Paper | Material | doi.org/10.13182/NT92-A34755
Articles are hosted by Taylor and Francis Online.
Three multigroup neutron cross-section libraries are used in synthesized three-dimensional discrete ordinates transport analyses to investigate their similarities, differences, and results for pressurized water reactor (PWR) pressure vessel surveillance dosimetry and shielding applications. The accurate determination of the neutron energy spectra and key exposure parameters, such as the integrated fast flux and total displacement per atom (dpa) within the pressure vessel wall, is very important for surveillance capsule analysis, pressure vessel embrittlement calculations, pressure-temperature curve calculations, and plant life extension planning. The accuracy of any radiation transport analysis depends in part on the cross-section library used to model the various materials. The calculated-to-experimental (C/E) ratios and the calculated reaction rates of several fast reactions are compared for the BUGLE-80, SAILOR, and ELXSIR cross-section libraries at the 97-deg surveillance capsule of the San Onofre Nuclear Generation Station Unit 2 (SONGS-2) and at the 90- and 97-deg (C/E ratios only) cavity dosimetry locations for another PWR (referred to as Reactor X). Additionally, the displacement per atom per second attenuation through the pressure vessel wall is compared with that of the integrated fast neutron flux (E>1.0MeV) and with the attenuation functions given in U.S. Nuclear Regulatory Commission Regulatory Guide 1.99, Revisions 1 and 2. Finally, the pressure vessel wall exposure sensitivity to fast neutrons due to vessel eccentricity and the buildup of 239Pu in the core region are also reported. The C/E ratios calculated using ELXSIR with the updated iron cross sections for SONGS-2 are fairly close to unity compared with those calculated using the other two cross-section libraries. The Reactor X C/E ratios are close to unity using the BUGLE-80 and SAILOR libraries and much higher than unity (∼1.7) for ELXSIR with the updated iron cross sections at two cavity dosimetry locations (90 and 97 deg). The large C/E ratio is believed to be caused by vessel eccentricity. The ELXSIR cross-section library with the updated iron cross sections also produced much higher calculated reaction rates for both reactors. The fast flux (E>1.0 MeV) through the pressure vessel wall increases by 17% when the SONGS-2 core and core barrel are moved 1.27 cm closer to the pressure vessel wall to simulate vessel eccentricity. The fast flux also increases by as much as 10% for SONGS-2 and 15% for Reactor X when a mixed fission spectrum (plutonium and uranium) is used to model the neutron source in the core region. Finally, the two attenuation functions (fast flux and dpa) given in Regulatory Guide 1.99, Revisions 1 and 2, differed from the plantspecific calculation for both SONGS-2 and Reactor X.
