ML092390194 

UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

OFFICE OF NUCLEAR REACTOR REGULATION 

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS 

WASHINGTON, DC 20555-0001 

October 7, 2009 

NRC INFORMATION NOTICE 2009-20: DEGRADATION OF WIRE ROPE USED IN FUEL 

HANDLING APPLICATIONS 

ADDRESSEES

All holders of operating licenses or construction permits for nuclear power reactors. All 

licensees who store spent fuel under Title 10 of the Code of Federal Regulations, Part 72, 

“Licensing Requirements for the Independent Storage of Spent Nuclear Fuel, High-Level 

Radioactive Waste, and Reactor-Related Greater Than Class C Waste.” 

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert 

addressees to possible degradation mechanisms affecting wire rope that may have an adverse 

impact on safe fuel handling operations. The NRC expects recipients to review the information 

for applicability to their facilities and consider actions, as appropriate, to avoid similar problems. 

However, suggestions contained in this information notice are not NRC requirements; therefore, 

no specific action or written response is required. 

DESCRIPTION OF CIRCUMSTANCES 

LaSalle Refueling Machine

In January 2009, during the twelfth refueling outage at the LaSalle County Station, Unit 2, 

Exelon Generation Company (the licensee) noted that one of the two redundant wire ropes in 

the main hoist of the refueling machine had broken wire strands at the entry to a terminal end 

fitting. A refueling operator had noted a sudden movement in the refueling machine while 

hoisting a fuel assembly to near the full up position. The refueling staff placed the fuel assembly 

in a safe location, inspected the refueling machine, and identified the damaged wire rope. The 

licensee quarantined the damaged rope for analysis, replaced the two wire ropes in the main 

hoist, and resumed refueling operations. 

The licensee conducted an evaluation of the damaged main hoist wire rope. The main hoist 

raises and lowers the fuel grapple mounted on the bottom of a telescoping mast. Two separate 

wire ropes run from the hoist drum, over equalizer sheaves, and down the inside of the mast, 

where they terminate at the inner mast section. The two wire ropes normally share the load, but 

the design of the hoist allows either wire rope to independently support a fully-loaded mast with 

substantial reserve capacity. The broken wire strands occurred at one of the terminal 

connections. The wire rope had a rotation-resistant construction, where the inner core strands 

are twisted in the opposite direction from the outer strands. The licensee had previously noted 
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that the wire rope may be subject to side (bending) forces at the terminal fitting when the mast 

was stowed in the full up position for maintenance. Analysis of the damaged rope section 

revealed that fatigue caused the wire strands to fail. The rotation-resistant construction of the 

wire rope used at LaSalle and the presence of the end fitting made inspection of the wire rope at 

the damaged location particularly difficult. The licensee’s corrective actions included fleet-wide 

inspection of wire rope in similar use and establishment of a program to replace these wire 

ropes on a set frequency. 

Beaver Valley Fuel Up-Ender

In October 2007, during a refueling outage at the Beaver Valley Power Station, Unit 1, First 

Energy Nuclear Operating Company (the licensee) noted that a stainless steel wire rope failed 

completely (all wire strands broken) on the fuel building up-ender. At the time of failure, a new 

fuel assembly was in the up-ender. When the supporting wire rope failed, the up-ender pivoted 

from a slightly inclined position to a fully horizontal position. 

The fuel building up-ender consists of a stainless steel frame that supports one fuel assembly at 

a time. The frame pivots from vertical to horizontal positions around a pin support on one end of 

the frame. To raise and lower the up-ender, operators use an electric winch connected by a 

wire rope through a series of three sheaves to the up-ender frame; thus, within a short distance, 

a section of the wire rope undergoes bending cycles in three different directions during each 

movement of the up-ender. 

The licensee determined that fatigue caused the wire rope to fail completely. The failure 

occurred between two offsetting sheaves, when the wire rope was near its peak loading. The 

licensee found the wire rope had been in service for 24 years, and the failure occurred in a 

section of the wire rope that, because of interference from the sheaves, may not have received 

a complete underwater visual inspection. Since the failure was limited to the wire rope, the 

licensee replaced the failed rope and resumed refueling operations but did not load the new fuel 

assembly into the reactor core. Other corrective actions included establishing new repetitive 

preventive-maintenance tasks to perform fuel transfer equipment cable and sheave inspections 

at both Beaver Valley Power Station Unit No. 1 and Unit No. 2. 

Browns Ferry Reactor Building Crane

On October 4, 2007, while making preparations for dry run activities related to dry cask storage 

at Browns Ferry, the Tennessee Valley Authority (the licensee) identified the degradation of one 

of the main hoist cables for the overhead crane in the reactor building. The degradation 

involved the partial untwisting of the wire rope strands within the stationary section of one wire 

rope. 

The Browns Ferry reactor building has a single-failure-proof crane with two independent wire 

ropes. Each wire rope is capable of safely handling the rated 125-ton load. Each wire rope has 

one end clamped to the hoist drum, unspools from the drum to the first load block sheave, 

passes several times between the load block sheaves and the upper sheaves attached to the 

trolley, and travels from the final load block sheave to a terminal end fitting attached to the 

trolley. The wire rope is stationary (i.e., neither bends around sheaves nor moves with respect 
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to the trolley) at the end between the highest position of the load block and the terminal end 

fitting. The crane was fitted with two right regular lay wire ropes. One of the wire ropes was 

installed slightly untwisted to reduce the tendency of the load block to twist. The action of the 

sheaves as the load block was lowered and raised concentrated the uneven twist in the 

stationary section of wire rope, causing the strands to untwist in this area. 

The licensee evaluated the physical condition of the wire rope, using the guidelines of the 1976 

version of American Society of Mechanical Engineers Safety Standard B30.2, “Overhead and 

Gantry Cranes (Top Running Bridge, Single or Multiple Girder, Top Running Trolley Hoist),” 

which the licensee had committed to follow. Consistent with those guidelines, the licensee and 

the crane vendor determined that, although the wire rope was somewhat distorted, it retained 

sufficient strength to support continued operation. However, the licensee implemented an 

enhanced inspection schedule to monitor the condition of the wire rope until the distorted rope 

could be replaced. The licensee subsequently replaced the wire ropes. 

BACKGROUND

Nuclear power plants use wire ropes in a broad range of material handling applications, 

including fuel handling, refueling, and dry storage. Safe conduct of these activities depends on 

the retention of adequate strength in the wire rope supporting the load. A wire rope’s strength 

comes from the integration of several individual wire strands into a well-ordered structure. 

Damage to multiple wire strands in a single location or loss of the well-ordered structure results 

in a substantial reduction in strength and the potential for rope failure. 

Fatigue is a common cause of wire rope damage in nuclear plant fuel handling applications. 

Each time the wire rope bends and returns to a straight configuration, it undergoes a complete 

bending cycle. The wire strands on the outside of the bend experience the greatest change in 

stress, and this stress is concentrated at points where individual wires in the outer wire strands 

pass over an inner wire strand. Repeated bending cycles lead to hardening and subsequent 

brittle failure of individual wires. Thus, fatigue failure is more likely to occur in regions of the 

wire rope subject to the most frequent bending (i.e., wire rope that passes around the most 

sheaves) during operation. 

As multiple wires fail in a single location, the load increases the stress on the remaining intact 

wires. Eventually, the remaining wires may have insufficient strength to support the load, and 

tensile overload may cause the last remaining wires to fail in a ductile manner. 

DISCUSSION

The LaSalle licensee experienced a partial failure (broken wire strands) of one of two wire ropes 

supporting the refueling mast at well below the rated load of the wire rope. The broken wire 

strands occurred at a point that was subject to small-radius bending and was difficult to inspect 

because it was located at an end fitting. While the redundant wire rope had no broken wire 

strands, it was subject to similar operating conditions. An installed equalizer assembly provides 

a means to compensate for variations in the lengths of the two ropes and maintains 

substantially equal rope loading. Had similar damage existed on the second rope and the first 

wire rope failed completely, the second wire rope also may have failed because of the sudden 
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increase in its load. Failure of both of the redundant wire ropes could have resulted in a drop of 

an irradiated fuel assembly and a consequential release of radioactive material. In situations 

where redundant wire ropes are used and are difficult to inspect, licensees may consider 

staggered replacement (i.e., replacement of individual wire ropes at widely separated times) or 

early simultaneous wire rope replacement (i.e., replacement of both ropes well before wire rope 

replacement criteria are satisfied) to avoid operation with both wire ropes in a severely 

degraded state. 

The Beaver Valley licensee experienced a complete failure of the sole wire rope used to 

position the fuel up-ender, with a new fuel assembly in the up-ender. The failure occurred at a 

point that was subject to repeated bending around two closely-spaced sheaves, was under 

maximum load (i.e., the fuel assembly was near horizontal in the up-ender), and was difficult to 

inspect because of the underwater location near the sheaves. Had the event occurred with a 

brittle, irradiated fuel assembly in the up-ender, the event could also have resulted in a release 

of radioactive material. 

The Browns Ferry licensee experienced a distortion (untwisting) of the wire rope structure in one 

of the two redundant reeving systems that support heavy loads moved on the refueling floor. 

Distortion of the wire rope structure can increase the potential for failure under load because the 

individual strands are less likely to share the load evenly. Proper control of the wire rope twist 

during the reeving process prevents this type of rope distortion. 

CONTACT

This information notice requires no specific action or written response. Please direct any 

questions about this matter to the technical contact listed below or, for reactor licensing issues, 

to the appropriate project manager in the Office of Nuclear Reactor Regulation (NRR). 

/RA by RLorson for/ /RA/ 

 William Brach, Director Timothy J. McGinty 

 Division of Spent Fuel Storage Division of Policy and Rulemaking 

 and Transportation Office of Nuclear Reactor Regulation 

 Office of Nuclear Material Safety 

 and Safeguards 

Technical Contact: Steve Jones, NRR 

301-415-2712 

E-mail: Steve.Jones@nrc.gov 

Note: NRC generic communications may be found on the NRC public Web site, 

http://www.nrc.gov, under Electronic Reading Room/Document Collections. 
IN 2009-20 

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increase in its load. Failure of both of the redundant wire ropes could have resulted in a drop of 

an irradiated fuel assembly and a consequential release of radioactive material. In situations 

where redundant wire ropes are used and are difficult to inspect, licensees may consider 

staggered replacement (i.e., replacement of individual wire ropes at widely separated times) or 

early simultaneous wire rope replacement (i.e., replacement of both ropes well before wire rope 

replacement criteria are satisfied) to avoid operation with both wire ropes in a severely 

degraded state. 

The Beaver Valley licensee experienced a complete failure of the sole wire rope used to 

position the fuel up-ender, with a new fuel assembly in the up-ender. The failure occurred at a 

point that was subject to repeated bending around two closely-spaced sheaves, was under 

maximum load (i.e., the fuel assembly was near horizontal in the up-ender), and was difficult to 

inspect because of the underwater location near the sheaves. Had the event occurred with a 

brittle, irradiated fuel assembly in the up-ender, the event could also have resulted in a release 

of radioactive material. 

The Browns Ferry licensee experienced a distortion (untwisting) of the wire rope structure in one 

of the two redundant reeving systems that support heavy loads moved on the refueling floor. 

Distortion of the wire rope structure can increase the potential for failure under load because the 

individual strands are less likely to share the load evenly. Proper control of the wire rope twist 

during the reeving process prevents this type of rope distortion. 

CONTACT

This information notice requires no specific action or written response. Please direct any 

questions about this matter to the technical contact listed below or, for reactor licensing issues, 

to the appropriate project manager in the Office of Nuclear Reactor Regulation (NRR). 

/RA by RLorson for/ /RA/

 

 William Brach, Director Timothy J. McGinty 

 Division of Spent Fuel Storage Division of Policy and Rulemaking 

 and Transportation Office of Nuclear Reactor Regulation 

 Office of Nuclear Material Safety 

 and Safeguards 

Technical Contact: Steve Jones, NRR 

301-415-2712 

E-mail: Steve.Jones@nrc.gov 

Note: NRC generic communications may be found on the NRC public Web site, 

http://www.nrc.gov, under Electronic Reading Room/Document Collections. 

ADAMS Accession Number: ML092390194 ME0948 

OFFICE SBPB:DSS TECH EDITOR BC:SBPB:DSS D:DSS PGCB:DPR 

NAME SJones KAzariah-Kribbs GCasto WRuland DBeaulieu 

DATE 9/16/09 via e-mail 9/8/09 via e-mail 9/18/09 9/21/09 9/21/09 

OFFICE PGCB:DPR BC:PGCB D:DSFST D:DPR 

NAME CHawes CMH MMurphy WBrach(RLorson for) TMcGinty 

DATE 9/22/09 9/30/09 10/07/09 10/07/09 

OFFICIAL RECORD COPY