Information Notice No. 85-12: Recent Fuel Handling Events
SSINS No.: 6835
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
February 11, 1985
Information Notice No. 85-12: RECENT FUEL HANDLING EVENTS
All nuclear power reactor facilities holding an operating license (OL) or
construction permit (CP).
This information notice is provided as a notification of potentially signif-
icant problems pertaining to recent fuel handling events. This notice
supplements Information Notice 80-01, which discussed similar events. It is
expected that recipients will review the information for applicability to
their facilities and consider actions, if appropriate, to preclude similar
problems from occurring at their facilities. However, suggestions contained
in this information notice do not constitute NRC requirements; therefore, no
specific action or written response is required.
Description of Circumstances:
Two events have occurred recently at nuclear power plants in which fuel was
dropped because of failures or deficiencies in hoist equipment. More details
are provided in Attachment 1.
(1) At Hatch 1 on October 6, 1984, a spent fuel bundle was dropped into its
storage cell because of a possible inadvertent actuation of the fuel
grapple hook position switch. The switch cover was missing.
(2) At Millstone 2 on November 8, 1984, a fuel pin dropped in the spent
fuel pool during fuel assembly reconstitution because the gripping
collet fingers slipped.
Several additional events have occurred that are noteworthy because they
involve deficiencies or maloperation of fuel handling equipment or proce-
dures. These are briefly summarized below; more detailed information is
given in Attachment 1.
(1) At Monticello on November 29, 1984, a spent fuel bundle handle was
deformed during transportation because of inadequate cask loading
(2) At Palisades on April 4, 1984, a new fuel bundle was stuck in the
refueling machine because of inadequate spreader bar air supply
February 11, 1985
Page 2 of 2
(3) At Turkey Point 4 on April 5, 1983, a spent fuel assembly dropped back
into its storage cell when the hoist limit switches failed to prevent
upward movement of the assembly. This event also involved a procedural
inadequacy concerning these limit switches.
(4) A second event at Turkey Point 4 on April 17, 1983, resulted in an
improperly loaded (leaning) fuel assembly.
(5) At Cook 1 on June 19, 1981, a fuel assembly was damaged in a collision
with a shield wall because an entangled air hose had tripped a limit
(6) Also at Cook 1 on August 4, 1982, a fuel assembly was cocked and lodged
in the manipulator bridge mast because the fuel handling procedures
were not properly followed.
This information notice briefly describes several events involving failures
or deficiencies in fuel handling equipment or procedures. In addition,
Information Notice 80-01 discusses two similar events at Pilgrim. In one, a
spent fuel assembly was inadvertently raised high enough in the fuel pool to
activate area radiation alarms because the lifting hook was caught between
the lifting bail and the assembly channel. In the other, a new fuel assembly
dropped onto the top of the storage fuel racks when the auxiliary hook
latching device failed to hold the lifting bail when the assembly struck the
top edge of the racks. The radiological consequences of these events were
minimal. Nevertheless, the events are considered significant, in that they
could have compromised plant safety and could have been prevented. Licensees
may wish to review their procedures in view of these events.
No specific action or written response is required by this information
notice. If you have any questions about this matter, please contact the
Regional Administrator of the appropriate NRC regional office or this
Edward L. Jordan, Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contact: C. V. Hodge, IE
1. Description of Recent Fuel Handling Events
2. List of Recently Issued IE Information Notices
February 12, 1985
Page 1 of 3
Description of Recent Fuel Handling Events
This event involved a possible inadvertent actuation of the fuel grapple
hook position switch. On October 6, 1984, with core unloading in progress, a
spent fuel bundle was inadvertently dropped into its storage rack cell (a
distance of about 12 feet), slightly deforming and scratching the bundle and
rack. Before the event, no trouble had been experienced in grappling
bundles. When the bridge operator lowered the affected bundle and detected
contact of the bundle with the rack, he stopped to align the bundle with its
storage cell; then the bundle dropped. The licensee declared an unusual
event and terminated it on confirming that no fission gases had been
Grapple tests and operator interviews indicated that the operator actions
required to position or rotate the fuel bundle could have resulted in
inadvertently operating the fuel grapple hook position actuation switch.
General Electric Service Information Letter (SIL) No. 298, dated August
1979, describes the potential for inadvertent switch operation in
conjunction with a slack grapple hoist cable before the operator has
verified that the fuel bundle is properly seated. General Electric
recommends that the owners of BWRs 1 through 4 install a commercially
available snap cover over the switch. The licensee had installed the switch
coVers on the refueling platforms of Units 1 and 2; however, between 1979
and the present, the covers had been removed. The licensee originally used
an epoxy-type adhesive to secure the covers, but now has bolted them into
This event involved mechanical slipping of the fuel holding mechanism. On
November 8, 1984, during fuel assembly reconstitution in the spent fuel
pool, a single spent fuel pin was dropped during eddy current testing for
cladding defects. The pin was gripped by collet fingers inside a long
cylindrical probe. Evidently these fingers slipped, possibly because of a
weld repair at the top of the pin. The fingers were adjusted to provide a
more positive grip. Although this pin was retrieved, inspected, and showed
no defects, it was replaced in its position in the fuel assembly by a
stainless steel spacer. The licensee instituted an additional check for
proper gripping of each fuel pin and completed the fuel assembly
This event illustrates the need for an explicit checkpoint in the fuel cask
loading procedure. On November 29, 1984, the handle on a spent fuel bundle
was found deformed when it was off-loaded from a transportation cask to a
storage rack at the GE Morris spent fuel storage facility. The bundle had
not been seated properly in the cask because horizontal tabs at the top of
the bundle had not been aligned properly with the cask, preventing the
bundle from being fully inserted. No radiological effects were caused, but
the event is significant because the fuel loading procedures were not
February 12, 1985
Page 2 of 3
Surveillance was conducted for this loading of the cask, but there was not
an explicit check for proper seating of the bundles before the cask cover
was bolted in place. The licensee's corrective action is to institute such
an explicit check in the fuel loading procedures.
This event involved inoperability of the fuel hoist mechanism. On April 4,
1984, while reloading the core, a new fuel bundle stuck in the refueling
machine. A combination of low spreader bar air supply pressure (40 psi vs
normal 50 psi) and air leakage from the spreader bar retraction hose fitting
resulted in the spreader bar extending downward one inch below the hoist
bottom. An interlock for the extended spreader bar prevented movement of the
bridge trolley. After evaluating the situation, the licensee increased the
air supply pressure and inserted the bundle into the core. The licensee then
completed core reload without further problem.
Turkey Point 4
This event involved a malfunction of the limit switches on the spent fuel
pit hoist and disclosed a procedural inadequacy. On April 5, 1983, during
refueling after a six month outage for steam generator repair, partially
burned fuel assembly X-13 was being lifted from its storage rack. The limit
switches failed to stop the upward movement of X-13, resulting in parting of
the hoisting cable and causing the assembly to drop back into its rack.
The crane design provides two different limit switches to restrict upper
motion: a power circuit limit switch and a geared limit switch. About three
weeks before actual fuel movement, testing indicated the switches would
work, but the investigation after the event revealed that a linkage in the
power limit switch was unhooked, which disabled the trip feature, and the
geared limit switch was out of adjustment. Had the licensee tested the upper
limit switch under no load at the beginning of each shift,as required by
OSHA regu-lations [29 CFR 1910.179(n)(4)] or recommended by industry
guidance (ANSI B30.2-1976, "Overhead and Gantry Cranes"), this event could
have been prevented.
The procedural inadequacy was the incorrect designation of the limit
switches. The spent fuel pit crane test procedure indicated that the power
circuit switch backed up the geared switch; the operating procedure for that
crane incorrectly indicated the opposite. The operating procedure also
contradicted the prohibition stated in both procedures against using the two
switches as normal stopping devices.
A second event occurred shortly afterward in which improper placement of a
fuel assembly into the core was not readily detected. Because of the X-13
drop, it was necessary to reconfigure the core loading sequence. Because
only the central area was to be reconfigured, the approved fuel loading
sequence started with assemblies on the core perimeter and spiraled inward.
This sequence only provided one or two adjacent surfaces (fuel or baffle
plate), instead of the usual four, to guide an assembly being inserted.
February 12, 1985
Page 3 of 3
On April 17, 1983, a small maladjustment of the fuel handling bridge
position (less than an inch deviation) coupled with a slight bow in
twice-burned fuel assembly X-04 led to placing X-04 astride of one of the
two locating pins in its intended core position. As a result, X-04 fell over
so that it leaned at a 35 degree angle against two other assemblies in the
core. Vessel lighting was such that the leaning assembly was not noticed
until four additional assemblies had been loaded, about an hour after the
presumed fall. No release of fission products occurred.
During refueling operations on June 19, 1981, a fuel assembly was damaged by
striking a shield wall retaining lip located in the refueling cavity,
approximately six inches high and several feet west of the reactor vessel.
The assembly was being transported toward the fuel transfer area by the
manipulator crane, but a fouled interlock had apparently allowed the gripper
"full up" indicating light to come on without the assembly being fully
inside the gripper tube. As a result of the collision, one fuel rod from the
15 x 15 assembly dropped to the cavity floor and lodged behind a ladder.
Three other rods appeared bent. The interlock did not operate correctly
because an entangled air hose had tripped a limit switch.
A year later, a similar event occurred. During refueling operations on
August 4, 1982, fuel movement was suspended when the refueling equipment was
incorrectly operated. This resulted in a fuel assembly becoming cocked and
lodged in the manipulator bridge mast. The upender device had not been
raised to the vertical position before the fuel assembly was lowered. This
caused the assembly to slide along the upender cable and give the bridge
operator a low load indication. Thinking the fuel assembly was rubbing in
the transfer assembly, the operator proceeded to lift the fuel assembly
until it became lodged and bent between the mast and the cable, giving a
high load reading. The licensee then investigated what had happened and
suspended fuel movement. Under an approved special procedure, the cable was
slackened. The assembly returned to its former shape except for minor
deformation and marks on a few fuel rods.
This event involved a violation of a technical specification requiring that
procedures be followed. The crane operator had failed to immediately stop
and evaluate the situation (according to procedure) when he observed an
unexplained load change while lowering a fuel assembly into the transfer
container. The crane operator also failed to check whether this container
was in a position to receive fuel.
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