Information Notice 1985-12, Recent Fuel Handling Events
| ML031180626 | |
| Person / Time | |
|---|---|
| Issue date: | 02/11/1985 |
| From: | Jordan E NRC/IE |
| To: | |
| References | |
| IN-85-012, NUDOCS 8502060449 | |
| Download: ML031180626 (6) | |
SSINS No.: 6835 IN 85-12 UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555 February 11, 1985 IE INFORMATION NOTICE NO. 85-12: RECENT FUEL HANDLING EVENTS
Addressees
All nuclear power reactor facilities holding an operating license (OL) or
construction permit (CP).
Purpose
This information notice is provided as a notification of potentially signifi- cant problems pertaining to recent fuel handling events. This notice supple- ments Information Notice 80-01, which discussed similar events. It is expected
that recipients will review the information for applicability to their facili- ties and consider actions, if appropriate, to preclude similar problems from
occurring at their facilities. However, suggestions contained in this informa- tion 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 I 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 procedures.
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 procedures.
(2) At Palisades on April 4, 1984, a new fuel bundle was stuck in the refueling
machine because of inadequate spreader bar air supply pressure.
85020 41
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IN 85-12 February 11, 1985 (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
switch.
(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.
Discussion:
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 office.
ward L. Jordan, D rector
2ubdvision of Emerge cy Preparedness
and Engineering esponse
Office of Inspection and Enforcement
Technical Contact:
C. V. Hodge, IE
(301) 492-7275 Attachments:
1. Description of Recent Fuel Handling Events
2. List of Recently Issued IE Information Notices
Attachment 1 IN 85-12 February 12, 1985 Description of Recent Fuel Handling Events
Hatch 1 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 released.
Grapple tests and operator interviews indicated that the operator actions
required to position or rotate the fuel bundle could have resulted in inadver- tently 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 place.
Millstone 2 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 lono 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 arip.
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 reconstitution.
Monticello
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
fullv inserted. No radiological effects were caused, but the event is signifi- cant because the fuel loading procedures were not carefully followed.
Attachment 1 IN 85-12 February 12, 1985 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.
Palisades
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 refuel- ing 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 hoist- ing 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
regulations [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 prohibi- tion stated in both procedures against using the two. switches as normal stop- ping 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.
Attachment 1 IN 85-12 February 12, 1985 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.
Cook 1 During refueling operations on June 19, 1981, a fuel assembly was damaged by
striking a shield wall retaining lip located in the refueling cavity, approxi- mately six inches high and several feet west of the reactor vessel. The assem- bly 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 incor- rectly 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.
4 Attachment 2 IN 85-12 February 11, 1985 LIST OF RECENTLY ISSUED
IE INFORMATION NOTICES
Information Date of
Notice No. Subject Issue Issued to
85-11 Licensee Programs For 2/11/85 All power reactor
Inspection Of Electrical facilities holding
Raceway And Cable Installation a CP
85-10 Posttensioned Containment 2/6/85 All power reactor
Tendon Anchor Head Failure facilities holding
85-09 Isolation Transfer Switches 1/31/85 All power reactor
And Post-Fire Shutdown facilities holding
85-08 Industry Experience On 1/30/85 All power reactor
Certain Materials Used In facilities holding
Safety-Related Equipment an OL or CP
85-07 Contaminated Radiography 1/29/85 All NRC licensees
Source Shipments authorized to
possess industrial
radiography sources
85-06 Contamination of Breathing 1/23/85 All power reactor
Air Systems facilities holding
85-05 Pipe Whip Restraints 1/23/85 All power reactor
facilities holding
85-04 Inadequate Management Of 1/17/85 All power reactor
Security Response Drills facilities holding
fabrication & pro- cessing facilities
85-03 Separation Of Primary Reactor 1/15/85 All pressurized water
Coolant Pump Shaft And power reactor
Impeller facilities holding an
85-02 Improper Installation And 1/15/85 All power reactor
Testing Of Differential facilities holding
Pressure Transmitters an OL or CP
OL = Operating License
CP = Construction Permit