Heat generation and corresponding energy saving in nuclear reactor shielding facilities due to g-rays energy variation G.C. Bakos* Democritus University of Thrace, Department of Electrical Engineering, Laboratory of Nuclear Technology, 67 100 Xanthi, Greece Received 25 January 2002; accepted 5 March 2002 Abstract This paper deals with the energy generation within shielding materials when single energy photons of 1.43 and 2.75 MeV, emitted from V 52 and Na 24 disc source respectively penetrate single layer shields of Al, Fe, Pb and graphite. The calculation is carried out using the build up factor method. A comparison has been made in order to estimate the percentage of energy saving for each photon energy and shielding material. Also the theoretical and experimental build up factors, used for the energy generation calculation, are presented. The theoretical scalar flux, calculated using the Monte-Carlo code SAM-CE, was applied for the theoretical build up factor calculation. The scalar flux measured directly in experimental facilities was used for the experimental build up factor calculation. # 2002 Elsevier Science Ltd. All rights reserved. 1. Introduction The heat generation within a shield can be a primary consideration in its design, especially when the shield is for a high power reactor in which rather large tem- perature increases can be expected. Near a power reactor core the radiation levels are generally so high that severe local overheating can occur in structural parts. It is usually the responsibility of the shield designer to calculate this heating and to spe- cify maximum permissible thickness and required provision of cooling. The heating up of the shield itself can be utilised via a suitable flow of water on the outside of the Annals of Nuclear Energy 30 (2003) 55–62 www.elsevier.com/locate/anucene 0306-4549/03/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved. PII: S0306-4549(02)00036-1 * Tel.: +30-541-79725; fax: +30-541-79734. E-mail address: bakos@ee.duth.gr (G.C. Bakos).