Author: Apollonio, A.
Paper Title Page
WEPMU006 Architecture for Interlock Systems: Reliability Analysis with Regard to Safety and Availability 1058
 
  • S. Wagner, A. Apollonio, R. Schmidt, M. Zerlauth
    CERN, Geneva, Switzerland
  • A. Vergara-Fernandez
    ITER Organization, St. Paul lez Durance, France
 
  For ac­cel­er­a­tors (e.g. LHC) and other large ex­per­i­men­tal physics fa­cil­i­ties (e.g. ITER), the ma­chine pro­tec­tion re­lies on com­plex in­ter­lock sys­tems. In the de­sign of in­ter­lock loops, the choice of the hard­ware ar­chi­tec­ture im­pacts on ma­chine safe­ty and avail­abil­i­ty. While high ma­chine safe­ty is an in­her­ent re­quire­ment, the con­straints in terms of avail­abil­i­ty may dif­fer from one fa­cil­i­ty to an­oth­er. For the in­ter­lock loops pro­tect­ing the LHC su­per­con­duct­ing mag­net cir­cuits, re­duced ma­chine avail­abil­i­ty can be tol­er­at­ed since shut­downs do not af­fect the longevi­ty of the equip­ment. In ITER's case on the other hand, high avail­abil­i­ty is re­quired since fast shut­downs cause sig­nif­i­cant mag­net aging. A re­li­a­bil­i­ty anal­y­sis of var­i­ous in­ter­lock loop ar­chi­tec­tures has been per­formed. The anal­y­sis based on an an­a­lyt­i­cal model com­pares a 1oo3 (one-out-of-three) and a 2oo3 ar­chi­tec­ture with a sin­gle loop. It yields the prob­a­bil­i­ties for four sce­nar­ios: (1)- com­plet­ed mis­sion (e.g., a physics fill in LHC or a pulse in ITER with­out shut­down trig­gered), (2)- shut­down be­cause of a fail­ure in the in­ter­lock loop, (3)- emer­gen­cy shut­down (e.g., after a quench of a mag­net) and (4)- missed emer­gen­cy shut­down (shut­down re­quired but in­ter­lock loop fails, pos­si­bly lead­ing to se­vere dam­age of the fa­cil­i­ty). Sce­nario 4 re­lates to ma­chine safe­ty and to­geth­er with sce­nar­ios 2 and 3 de­fines the ma­chine avail­abil­i­ty re­flect­ed by sce­nario 1. This paper pre­sents the re­sults of the anal­y­sis on the prop­er­ties of the dif­fer­ent ar­chi­tec­tures with re­gard to ma­chine safe­ty and avail­abil­i­ty.