Community Research and Development Information Service - CORDIS

Abstract

IT HAS LONG BEEN KNOWN THAT, FOR LIGHT WATER REACTORS, THE TEMPERATURE COEFFICIENT OF REACTIVITY CALCULATED FROM MICROSCOPIC NUCLEAR DATA DIFFERS IN A SYSTEMATIC WAY FROM THAT OBTAINED IN CRITICAL EXPERIMENTS AS WELL AS IN THE START UP OPERATIONS OF LARGE POWER REACTORS. IN ORDER TO REMOVE THIS DISCREPANCY, IT HAS BEEN PROPOSED THAT THE ENERGY DEPENDENCE OF CERTAIN NUCLEAR DATA BE MODIFIED WITH RESPECT TO ENDF/B-V. IN PARTICULAR, THE 238U CAPTURE CROSS SECTION IN THE SUBTHERMAL AND THERMAL RANGE SHOULD DECREASE WITH ENERGY FASTER THAN 1/V, DUE TO THE PRESENCE OF A NEGATIVE ENERGY RESONANCE. THIS WAS MEASURED AT THE GEEL LINAC FOR BOTH A METALLIC AND AN OXIDE SAMPLE USING FOUR C(6)D(6) DETECTORS OPERATED IN COINCIDENCE. IN ORDER TO INCREASE THE NUMBER OF COLD NEUTRONS, A LIQUID METHANE MODERATOR MAINTAINED AT -170 C TEMPERATURE WAS INSTALLED AROUND THE NEUTRON PRODUCING TARGET. RELATIVE VALUES OF THE CROSS-SECTION TOGETHER WITH THEIR ESTIMATED UNCERTAINTIES ARE GIVEN DOWN TO 0.002 EV ENERGY AND COMPARED WITH THE PROPOSED SHAPE AS WELL AS WITH THE ENDF/B-B EVALUATION.

Additional information

Authors: CORVI F, JRC-GEEL;FIONI G JRC-GEEL, JRC-GEEL
Bibliographic Reference: PAPER PRESENTED: INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY, MITO/JAPAN, MAY 30, JUNE 3, 1988, AVAILABILITY: CEC-LUXEMBOURG, DG XIII/A2, BP 1907, MENTIONING PAPER ORA 33877 E
Availability: Can be ordered online
Record Number: 1989126223300 / Last updated on: 1989-04-01
Category: PUBLICATION
Available languages: en
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