PROCEDE ET APPAREIL POUR EMPECHER TOUTE CRITICITE INVOLONTAIRE DANS UNE CENTRALE ELECTRONUCLEAIRE

• Main Author: CHARLES RICHARD TULEY JR., DOUGLAS ARTHUR BAUMAN, MICHAL MARCELI FEILCHENFELD, LESLEY GREENBERG ET JAMES ALBERT NEUNER
• Format: Patent
• Language: French
• Published: 17.02.1984
• Subjects: NUCLEAR ENGINEERING; NUCLEAR PHYSICS; NUCLEAR POWER PLANT; NUCLEAR REACTORS; PHYSICS

PROCEDE ET APPAREIL POUR EMPECHER TOUTE CRITICITE INVOLONTAIRE DANS UNE CENTRALE ELECTRONUCLEAIRE.LE FLUX NEUTRONIQUE EST MESURE AU MOYEN D'UN DETECTEUR 63 QUI CREE DES SIGNAUX DE TAUX DE COMPTAGE DU FLUX ENVOYES PAR L'INTERMEDIAIRE D'UN PREAMPLIFICATEUR 65 ET D'UN AMPLIFICATEUR 67 A UN MICROCALCULATEUR 69. CE DERNIER CONVERTIT LES SIGNAUX RECUS EN SIGNAUX NUMERIQUES ET CALCULE LA VALEUR MOYENNE DU FLUX NEUTRONIQUE 4096 FOIS PAR MINUTE. A LA FIN DE CHAQUE MINUTE, LA DERNIERE VALEUR EST COMPAREE AVEC LA VALEUR OBTENUE 10 MINUTES AUPARAVANT ET SI LA DERNIERE VALEUR DEPASSE LA PREMIERE D'AU MOINS UN FACTEUR DE MULTIPLICATION PRESELECTIONNE, LE MICROCALCULATEUR ENVOIE UN SIGNAL D'ALARME A UN SYSTEME DE PROTECTION 71.APPLICATIONS : NOTAMMENT A LA DETECTION D'UNE DILUTION INVOLONTAIRE DU BORE DANS UN REACTEUR A EAU SOUS PRESSION A L'ARRET. An inadvertent approach to criticality in a nuclear fueled electric power generating unit is detected and an alarm is generated through on-line monitoring of the neutron flux. The difficulties of accurately measuring the low levels of neutron flux in a subcritical reactor are overcome by the use of a microcomputer which continuously generates average flux count rate signals for incremental time periods from thousands of samples taken during each such period and which serially stores the average flux count rate signals for a preselected time interval. At the end of each incremental time period, the microcomputer compares the latest average flux count rate signal with the oldest, and preferably each of the intervening stored values, and if it exceeds any of them by at least a preselected multiplication factor, an alarm is generated. The interval and multiplication factor are chosen such that an alarm is generated early enough in the event to provide adequate time for an automatic system or the operator to take action which prevents the reactor from going critical yet minimizes the likelihood of a spurious response. As applied to a pressurized water reactor system, boron dilution events are detected in time that the chemical and volume control system can be isolated and the valves for the refueling water storage tank can be opened to inject highly borated water into the reactor coolant system to keep the reactor subcritical.