ML20008F448
| ML20008F448 | |
| Person / Time | |
|---|---|
| Site: | 05000000 |
| Issue date: | 08/04/1981 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| IEIN-81-23, NUDOCS 8103300403 | |
| Download: ML20008F448 (2) | |
Text
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SSINS No.:
6835 Accession N
-p IMN IN 81-23 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 August 4, 1981 IE INFORMATION NOTICE NO. 81-23:
FUEL M SEMBLY DAMAGED DUE TO IMPROPER POSITIONING OF HANDLING EQUIPMENT Description of Circumstances:
On June 19, 1981, a spent fuel assembly at the D. C. Cook Unit 1 facility was damaged while being tr:nsferred in the refueling cavitv when the lower end of the assembly struck a ledge outside of the reactor vessel.
During lifting of the fuel assembly from the cort the two air lines and the electric cable serving the gripper tangled and caught the gripper-tube-up position switch, closing 't before the gripper tube and attached fuel assembly were in the full-up p)sition inside the cannister. Closing the switch cleared the inter-lock and i11 owed lateral movement of the manipulator crane.
The lower end of the fuel assembly protruded below the cannister and it struck the ledge on the refueling cavity floor just outside the reactor vessel area.
Several rods in the fuel assembly were damaged, and one rod was dislodged and fell from the assembly onto the refueling cavity floor.
No release occurred as a result of the damaged rods, even though the dislodged rod was severely bent. However, considerable time was lost due to efforts to recover the dislodged rod and te-move the damaged fuel assembly out of the refueling cavity.
Discussions with refueling personnel indicate that tangling of the air lines and electric cable is not an uncommon occurrence.
For example, manipulator crane cperators fre-quently must shake the gripper tube lines and cables to obtain a signal that the gripper has correctly engaged the fuel assembly.
Stearns Roger, manufacturer of the manipulator crane, has previously proposed modifications to improve the cranes, especially the earlier models. One of these modifications was the addition of the Z-axis tape that provides positive indication of the vertical position of the gripper tube assembly (and thus the fuel assembly).
The D. C. Cook unipulator cranes have the Z-axis tapes, but the operator (s) involved in the subject event apparently did not check the tape to verify the position of the assembly before initiating lateral movement.
The licensee has revised the fuel handling procedure to require the mani-pulator crane operators to check the Z-axis tape in addition to the limit lights to verify the fuel assembly is in the full-up position before the crane is moved.
(It has always been required by D. C. Cook procedures to utilize the tape to verify that the fuel assembly is in the full-dow1 position before the gripper is disengaged.)
A related event involving improper vertical positioning of the gripper tube assembly occurred at the Point Beach Unit 2 facility during the April-May 1981 refueling outage.
The gripper fingers were extended in the latch position underneath the leaf spring of the fuel assembly rather than under the top plate of the top nozzle. Again, the problem could have been avoided by checking the Z-axis tape.
n i
i IN 81-23 August 4, 1981 Page 2 of 2 All licensees and construction permit holders, particularly those with similar manipulator cranes, may wish to make equipment modifications to reduce the l
potential for this type of event.
In addition, operating procedures should i
be reviewed to assure that all available indications are fully utilized (i.e.,
i the Z-axis tapes, visual observation of the air lines and electrical cables, underwater visual observation using binoculars of movement of the fuel j
assemblies) to prevent this type of occurrence.
i This Information Notice is provided as a notification of a possible generic problem.
It is expected that recipients will review tne information for possible applicability to their facility.
It is also expected that copies of this Information Notice will be provided to personnel involved in fuel handling operations. No special action or response is requested at this time.
If you have any quastions regarding this matter, please contact the director of the appropriate NRC Regional Office, i
Attachment:
Recently issued IE Information Notices i
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.o 4-Attachment TN 81-23 August 4, 1981 RECENTLY ISSUED IE INFORMATION NOTICES Information Date of Notice No.
Subject Issue Issued to 81-22 Section 235 and 236 7/31/81 All power research Amendments to the reactor, fuel Atomic Energy Act fabrication and of 1954 reprocessing, and spent fuel storage licensees and applicants 81-21 Potential Loss of Direct 7/21/81 All power reactor Access to Ultimate Heat Sink facilities with an OL or CP 81-20 Test Failures of Electrical 7/13/81 All power reactor Penetration Assemblies facilities with an OL or CP 81-19 Lost Parts in Prir.ary 7/6/81 All pow r reactor Coolant System
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OL or CP facilities with an 81-18 Excessive Radiation 6/23/81 Specified licensees Exposures to the Fingers of holding byproduct Three Individuals Incurred licenses During Cleaning and Wipe Testing of Radioactive Sealed Sources at a Sealed-Source Manufacturing Facility 81-16 Control Rod Drive System 4/23'81 All BWR facilities Malfunctions with an OL or CP 81-15 Degradation of Automatic 4/22/81 All power reactor ECCS Actuation Capability facilities with an by Isolation of Instrument OL or CP Lines 81-14 Potential Overstress of 4/17/81 All power reactor Shafts on Fisher Series facilities with an 9200 Butterfly Valves OL er CP with Expandable T Rings OL = Operating Licenses CP = Construction Permits L