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Information Notice No. 83-35: Fuel Movement with Control Rods Withdrawn at BWRS
SSINS No.: 6835 IN 83-35 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, DC 20555 May 31, 1983 Information Notice No. 83-35: FUEL MOVEMENT WITH CONTROL RODS WITHDRAWN AT BWRS Addressees: All boiling water reactor facilities holding an operating license (OL) or construction permit (CP). Purpose: This information notice is provided as a notification of potentially significant events involving fuel loading in control cell locations where control rods are not fully inserted. It is expected that recipients will review the information for applicability to their facilities. No specific action or response is required at this time. Description: Brunswick 1 Event During a refueling outage on Saturday, January 22, 1983, five control rods in empty cell locations were uncoupled from their drive mechanisms to permit removal of the drives for maintenance. As work progressed, the rod drives were recoupled with the control rods because of pressure fluctuations in the rod drive fluid, thereby preventing the removal of the drive mechanisms from the reactor vessel. To avoid having a maintenance crew idle, a decision was made to proceed to other control rod drives requiring maintenance. By 3:00 a.m, on January 23, the shift foreman, after consultation with the nuclear engineer on shift, concluded that all applicable requirements had been met for a temporary change to the existing fuel movement procedure. The shift operating supervisor and the senior reactor operator on the refueling bridge approved the temporary change to bypass some steps in the existing procedure and proceed to the next 4 control cells requiring rod drive maintenance. Each of the 4 control cells contained a fuel assembly. These assemblies were subsequently moved to 4 other separate control cell locations according to the fuel movement procedure. During a routine rod position verification, approximately 9 hours after the 4 fuel assemblies were moved, it was discovered that the control rods in those cells were fully withdrawn. As mentioned above, the fuel movements were made in accordance with the as-written fuel movement procedure, but apparently were not reviewed to ensure that the control rods were fully inserted in those cells to which fuel was moved. These fuel movements were in violation of the licensee's technical specifications. 8305110461 . IN 83-35 May 31, 1983 Page 2 of 3 Duane Arnold Event During core loading operations on March 30, 1980, a fuel assembly would not set properly in its assigned location in control cell, 06-19. A temporary change was written to the fuel movement procedure to unload inspect, and reload that control cell. Upon completion of the steps to the change of the fuel movement procedure, the normal reload was resumed beginning with control cell 06-23. The first fuel assembly was moved into control cell 06-23. Before a second fuel assembly could be loaded into control cell 06-23, it was discovered that the control rod in that cell was not fully inserted. Inadvertently, the fuel movement procedure temporary change had eliminated a step to insert the control rod in the next cell (06-23) to be loaded. This fuel movement was in violation of the licensee's technical specifications. Discussion: Refueling interlocks are specified for all BWRs to prohibit fuel loading with any control rod withdrawn in order to prevent the possibility of criticality during refueling operations. Operating plant technical specifications have, however, allowed bypass of the refueling interlock signals to facilitate multiple control rod drive maintenance. The bypass of the refueling interlock signals was acceptable as long as several criteria were met, including the removal of the fuel assemblies surrounding the control rod to be withdrawn. Some technical specifications then evolved through utility negotiations with the NRC to permit fuel loading with control rods withdrawn. Subsequently the NRC issued the BWR Standard Technical Specifications (NUREG-0123) which reflected this position. Brunswick 1 operates under essentially standard technical specifications; Duane Arnold operates under custom technical specifications. Both versions allow fuel movement with multiple control rods withdrawn when specific conditions are met. General Electric recognized the potential problem in June 1982 and issued SIL No. 372 to clarify the original intent of the GE BWR technical specifications concerning refueling interlocks. It was recognized at this time that the potential for localized criticality and fuel damage does exist while loading fuel with control rods withdrawn for maintenance. General Electric recommended that each licensee review its present technical specifications and refuel and rod drive maintenance procedures and adopt the concept of suspended fuel loading whenever all control rods are not fully inserted. The original intent of the refueling interlocks is to prohibit the loading of fuel assemblies into the reactor vessel with multiple control rods withdrawn. Some operating plant technical specifications do not allow fuel loading in the reactor vessel with control rods withdrawn for maintenance and other plants may want to reflect this position in their station procedures. The NRC plans to reevaluate the Standard Technical Specifications governing fuel movement with multiple control rods withdrawn for maintenance. . IN 83-35 May 31, 1983 Page 3 of 3 No written response to this information notice is required. If you need additional information regarding this matter, please contact the appropriate NRC Regional Office, or this office. Edward L. Jordan Director Division of Emergency Preparedness and Engineering Response Office of Inspection and Enforcement Technical Contact: P. R. Farron (301) 492-4766 Attachment: Lit of Recently Issued Information Notices .
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