Headquarters Daily report MAY 16, 1995 *************************************************************************** REPORT NEGATIVE NO INPUT ATTACHED INPUT RECEIVED RECEIVED HEADQUARTERS X REGION I X REGION II X REGION III X REGION IV X *************************************************************************** PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION III MAY 16, 1995 Licensee/Facility: Notification: Northern States Power Co. MR Number: 3-95-0087 Prairie Island 1 2 Date: 05/16/95 Welch,Minnesota RI PC Dockets: 50-282,50-306 PWR/W-2-LP,PWR/W-2-LP Subject: ACTUATION OF CRANE PROTECTIVE FEATURE DURING LIFT OF SPENT FUEL STORAGE CASK. Reportable Event Number: N/A Discussion: At approximately 1:30 a.m. on May 13, 1995, while the licensee was lifting its loaded TN-40 spent fuel storage cask from the spent fuel pool, an actuation of the auxiliary building crane's overload sensing device occurred, and the crane controls shut down. When this occurred, the bottom of the cask was approximately 3 inches below the deck of the spent fuel pool and was unable to be moved laterally away from the pool. The overload sensing feature is part of the crane's "conventional hoist safety system" and is designed to actuate if a load equivalent to 110 percent of the crane rated load is sensed by a load cell. The rated load of the crane is 125 tons and the weight of the cask and lifting components on the auxiliary building crane was 123.75 tons, therefore the crane was not overloaded. The licensee verified that there was not a load hangup or two-block condition. The licensee's investigation identified that the load weighing system had provided a crane load input signal to the overload sensing system that was erroneously high. A representative of the crane vendor was onsite assisting the licensee with its investigation. The licensee's initial determination was that the load cell was incorrectly calibrated, the crane overload setpoint was set using an inaccurate methodology, and crane reeving system geometrical effects on the load cell resulted in premature actuation of the 110 percent overload trip. The licensee's onsite safety review committee reviewed a safety evaluation to bypass the overload trip and continue with the lift, contingent upon implementation of additional administrative controls to detect if an actual overload condition should occur. Other crane safety features were available to protect against overload, two-blocking, load hang-up, and rope break events. The licensee bypassed the 110 percent crane overload trip on the afternoon of May 13, continued with the cask lift, and set the cask into the auxiliary building decontamination area at approximately 7:00 p.m. Regional Action: The senior resident inspector was onsite when the event occurred. The resident inspectors reviewed the event, attended the licensee's safety review committee meetings, observed the installation of the crane trip bypass, and completion of the cask lift. The resident and regional inspectors will review the licensee' formal root cause evaluation of the event. The licensee has committed to not lift the cask again until the evaluation is complete and follow-on issues resolved. Contact: W. KROPP (708)829-9663