Agenda - 01-19-1999 - 9b1 - Laserfiche WebLink

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WAIS Document Retrieval configuration subsequent to the proposed activity and it has been shown that the consequences remain acceptable with respect to the same criteria used previously. Thus, there is no increase in consequences for fuel mislocation or misloading. Therefore it is concluded that the proposed changes do not significantly increase the probability or consequences of any accident previously evaluated. 2. Create the possibility of a new or different kind of accident from any previously analyzed. To assess the possibility of new or different kind of accidents, a list of the important parameters required to ensure safe fuel storage was established. Safe fuel storage is defined here as providing an environment, which would not present any significant threats to workers or the general public (i.e., meeting the requirements of 10 CFR 100 and 10 CFR 20). Any new events, which would modify these parameters sufficiently to place them outside of the boundaries analyzed for normal conditions and /or outside of the boundaries previously considered for accidents would be considered to create the possibility of a new or different accident. The criticality and radiological safety evaluations were reviewed to establish the list of important parameters. The fuel configuration and the existence of the moderator /coolant were identified as the only two parameters, which were important to safe fuel storage. Significant modification of these two parameters represents the only possibility of an unsafe storage condition. Once the two important parameters were established, an additional step was taken to determine what events (which were not previously considered) could result in changes to the storage configuration or moderator /coolant presence during or subsequent to the proposed changes. This process was adopted to ensure that the possibility of any new or different accident scenario or event would be identified. Due to the proposed activity, an accidental drop of a rack module during construction activity in the pool was considered as the only event which might represent a new or different kind of accident. A construction accident resulting in a rack drop is an unlikely event. The proposed activity will utilize the defense -in -depth approach for these heavy loads. The defense -in -depth approach is intended to meet the requirements of NUREG -0612 and preclude the possibility of a rack drop. All movements of heavy loads over the Pool will comply with the applicable administrative controls and guidelines (i.e. plant procedures, NUREG -0612, etc.). A temporary hoist and rack lifting rig will be introduced to lift and suspend the racks from the bridge of the Auxiliary Crane. These items have been designed in accordance with the requirements of NUREG -0612 and ANSI N14.6 and will be similar to those used recently to install storage rack modules in Pool 'B'. The postulated rack drop event is commonly referred to as a heavy load drop'' over the pools. Heavy loads will not be allowed to travel over any racks containing fuel assemblies. The danger represented by this event is that the racks will drop to the pool floor and the pool structure will be compromised leading to loss of moderator /coolant, which is one of the two important parameters identified above. Although the analysis of this event has been performed and shown to be acceptable, the question of a new or different type of event is answered by determining whether heavy load drops over the pool have been considered previously. As stated above, heavy loads (storage rack modules) were recently installed in Pool 'B' using similar methods. Therefore, the rack drop does not represent a new or different kind of accident. The proposed change does not alter the operating requirements of the plant or of the equipment credited in the mitigation of the design basis accidents. The proposed change does not affect any of the important parameters required to ensure safe fuel storage. Therefore, the potential for a new or previously unanalyzed accident Page 4 of 8 http: / /frwebgate2. acces ... /waisgate.cgi ?WAISdocID= 341284846 +0 +0 +0 &WAISaction = retriev 1/14/99