STARTUP AND PARAMETER MEASUREMENTS FOR PAKISTAN MNSR (PARR-Ⅱ)

The paper presents the main results of the startup and the preparation experi-ment for PARR-II. This reactor safely Went to critical on November 2nd 1989,and reached its rated flux level of 1×10~(12)n/cm~2.s on November 10th 1989. Maxi-mum operating time under the condition when the neutron flux at inner irradiationsite is 1.1×10~(12)n/cm~2.s is 6.75 hours. For the test of sudden reactivity release,the control rod was fully withdrawn i.e. 4mk of excess reactivity was released,about six minutes later the peak flux reached to 2.9×10~(12)n/cm.s. The results showthat the PARR-II possesses an inherent safety, various parameters met those stipu-lated in the contract. This reactor was formally put into use on November 14 th1989.