Information Notice 1986-06, Failure of Lifting Rig Attachment, While Lifting Upper Guide Structure at St. Lucie Unit 1: Difference between revisions

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{{#Wiki_filter:SSINS No.: 6835IN 86-06UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF INSPECTION AND ENFORCEMENTWASHINGTON, D.C. 20555February 3, 1986IE INFORMATION NOTICE NO. 86-06: FAILURE OF LIFTING RIG ATTACHMENT,WHILELIFTING THE UPPER GUIDE STRUCTURE ATST. LUCIE UNIT 1
{{#Wiki_filter:SSINS No.: 6835 IN 86-06 UNITED STATES NUCLEAR REGULATORY
 
COMMISSION
 
OFFICE OF INSPECTION
 
===AND ENFORCEMENT===
WASHINGTON, D.C. 20555 February 3, 1986 IE INFORMATION
 
NOTICE NO. 86-06: FAILURE OF LIFTING RIG ATTACHMENT,WHILE
 
LIFTING THE UPPER GUIDE STRUCTURE
 
AT ST. LUCIE UNIT 1  


==Addressees==
==Addressees==
:All nuclear power facilities holding an operating license (OL) or a constructionpermit (CP). .
:
All nuclear power facilities
 
holding an operating
 
license (OL) or a construction
 
permit (CP). .


==Purpose==
==Purpose==
:This notice is provided to advise licensees of a potentially significant problemthat occurred during the movement of a heavy load over the reactor core. It isexpected that recipients will review this information for applicability to theirfacilities and consider actions, if appropriate, to preclude similar problems attheir facilities. However, the suggestions contained in this notice do notconstitute NRC requirements; therefore, no specific action or written responseis required.
: This notice is provided to advise licensees
 
of a potentially
 
significant
 
problem that occurred during the movement of a heavy load over the reactor core. It is expected that recipients
 
will review this information
 
for applicability
 
to their facilities
 
and consider actions, if appropriate, to preclude similar problems at their facilities.
 
However, the suggestions
 
contained
 
in this notice do not constitute
 
NRC requirements;  
therefore, no specific action or written response is required.Description
 
of Circumstances:
On November 6, 1985, while lifting the upper guide structure
 
from the St.Lucie Unit 1 reactor vessel, licensee personnel
 
noticed the lifting rig tilt.The lift was immediately
 
stopped, with the lifting rig canted upward about 6 inches and the guide structure
 
canted downward about 6 inches at one of the three attachment
 
points. An attempt was promptly made to lower the'load back to its installed
 
position, but the load cells indicated
 
binding, so the attempt was terminated
 
after lowering the load a few inches. The 50-ton load was left suspended
 
about 8 feet above the reactor core.The licensee declared an Unusual Event. Core alteration
 
containment
 
integrity was enhanced by resuming full use of the airlocks.
 
Temporary
 
primary manway covers were installed
 
on bcth hot and cold legs to enhance the nozzle dams.Survey transits were set up and procedures
 
implemented
 
to monitor the rig and load for any shifts in their positions.
 
The licensee and the nuclear steam system supplier, Combustion
 
Engineering, designed and tested a supplementary
 
lifting rig to support the upper guide structure
 
from the upper portion of the normal rig, using a cable and J-hook system. On November 9 with the supplementary
 
rig installed, the load was jacked to a level orientation
 
and moved to its normal parking position in the refueling
 
pool.8601290056 IN 86-06 February 3, 1986 Damage caused during the incident included bending the lifting rig and one of the two guide pins that align the rig with the reactor vessel.Discussion:
The upper guide structure
 
is shown in Figure 1. It is supported
 
in the reactor vessel by it§..upper
 
flange. It is aligned by eight alignment
 
keys, four at the top and fourat the bottom. The structure
 
fits down inside the core support barrel, just'above
 
the fuel assemblies (see Figure 2). The fuel assembly alignment
 
plate is the bottom component
 
of the upper guide structure.
 
The lifting rig is attached to the upper guide structure
 
by three vertically
 
oriented bolts. These bolts are attached from above the water line by torque tools that run down the hollow columns of the rig (see Figure 3). Combustion
 
Engineering's
 
procedure
 
for attaching
 
the rig calls for checking for thread engagement
 
and torquing each bolt to 50 ft-lbs. The licensee's
 
procedure omitted the step concerning
 
the check for thread engagement.
 
Subsequent
 
inspection
 
of the bolt that had pulled loose indicated
 
that part of the last thread was stripped.
 
It is assumed that this bolt cross-threaded
 
or bound due to rig to guide structure
 
misalignment
 
during attachment
 
and reached the 50 ft-lb torque requirement
 
with only part of one thread engaged. During the lift, the few inches of unengaged
 
bolt shaft were pulled through the lifting rig until the bolt head rested on the rig's surface at the bottom of the column, resulting
 
in an imperceptible
 
tilt. The resulting
 
lateral load was initially
 
s6pported
 
by the guide pins. When the rig and guide structure
 
were lifted about 8 feet, where the guide bushings on the lifting rig reached the tapered portion of the guide pins, it is surmised that sufficient
 
lateral motion was permitted
 
to allow the thread of the improperly
 
engaged bolt to slip free. This caused the observed motion and tilt.After the guide structure
 
was supported
 
by the supplemental
 
lifting rig and leveled, it was moved to its normal parking position in the refueling
 
pool.The short attachment
 
bolts and torque tools were then replaced with full-length
 
bolts.- The long bolts are designed with heads that rest on surfaces at the top of the three hollow columns of the lifting rig. This has the advantage
 
of making anyflmck of full thread engagement
 
more apparent to the personnel attaching
 
the rig. The guide structure
 
was subsequently
 
returned to its installed
 
position using the long attachment
 
bolts.The licensee has not yet decided whether to permanently
 
modify the attachment
 
bolts. The licensee plans to review all reactor-related
 
lifts for adequacy of the procedures
 
to ensure proper lift rig attachment, including
 
provisions
 
for measuring
 
thread engagement.
 
The potential
 
consequences
 
of dropping heavy loads into the open reactor vessel were addressed
 
by Unresolved
 
Safety Issue (USI) A-36, "Control of Heavy Loads Near Spent Fuel." The concern for a UGS drop is that fuel assemblies
 
might be sufficiently
 
damaged to release the radioactive
 
gases and iodines held within the fuel-clad
 
gap. Under the reduced containment
 
integrity
 
requirements
 
for the refueling
 
mode, damage to several fuel assemblies
 
might cause the radiation dose limits of 10 CFR 100 to be exceeded.
 
IN 86-06 February 3, 1986 Plant specific calculations
 
were not made for a UGS drop at St. Lucie because the NRC determined
 
that further calculations
 
were not required after reviewing initial calculations
 
previously
 
submitted
 
by other reactor facilities
 
in response to Phase II of USI A-36. Some indication
 
of the consequences
 
of a UGS drop at St. Lucie can be gained from calculations
 
performed
 
by Combustion
 
Engineering
 
for a reactor vessel head drop at Waterford
 
3. The head drop calculations
 
assumed the reactor vessel head was sufficiently
 
tilted at impact to directly strike the UGS with the UGS at rest in its normal installed
 
posi-tion. The calculated
 
response velocity of the Waterford
 
UGS was 28 feet per second, and the resulting
 
vertical stresses imposed on the fuel were not sufficient
 
to rupture the cladding.If the St. Lucie UGS had dropped from an 8 foot elevation, its striking velocity would have been substantially
 
less than the UGS response velocity calculated
 
for the Waterford
 
head drop. However, the potential
 
for misalignment
 
of the recesses in the bottom of the UGS (i.e., the fuel assembly alignment
 
plate)with the fuel assembly upper end fitting posts was not addressed
 
by the Waterford scenario.
 
If substantial
 
misalignment
 
occurred, the fuel could be subjected
 
to additional
 
axial loading. Significant
 
misalignment
 
could not occur without substantial
 
impact damage to the eight keys and keyways, which would also result in a reduced striking velocity of the UGS as it reached the fuel. On this basis, significant
 
radioactive
 
gas release is considered
 
to be unlikely, although it has not been shown to be impossible.
 
No specific action or written response is required by this notice. If you have any questions
 
regarding
 
this matter, please contact the Regional Administrator
 
of the appropriate
 
NRC regional office or this office.ar Jordan, Director Divisio of Emergency
 
===Preparedness===
and gineering
 
Response Office of Inspection
 
and Enforcement
 
Technical
 
Contacts:
S. M. Long, IE (301) 492-7159 D. E. Sells, NRR (301) 492-9735 Attachments:
1. Figure 1, Upper Guide Structure
 
Assembly 2. Figure 2, Reactor Internals
 
Assembly 3 Figure 3, Upper Guide Structure
 
Lifting Rig 4. List of Recently Issued IE Information
 
Notices
 
Attachment
 
1 IN 86-06 February 3, 1986 EXPANSION COMPENSATING
 
RING CEA SHROUD GRID ASSEMBLY.CEA SHROUDS FUEL ASSEMBLY ALIGNMENT
 
PLATE Figure 1: Upper Guide Structure
 
Assembly (St. Lucie Unit 1 FSAR-figure
 
4.2-10)
UPPER GUIDE-STRUCTURE
 
SUPPORT PLATE Attachment
 
2 IN 86-06 February 3, 1986 CEA SHROUD IN-CORE-INSTRUMENTATION
 
GUIDE TUBE OUTLET CORE' SUPPORT BARREL FUEL ALIGNMENT PINS CORE-SUPPORT ASSEMBLY Am. 3-7/85 Figure 2: Reactor Internals
 
Assembly (St. Lucie Unit 1 FSAR figure 4.2-7)
At ta chment3 IN 86-06 February 3, 1986 LIFT POINT FOR CRANE HOOK CLEVIS ASSEMBLY WORKING PLATFORM I NSTRUMENT STALK OPENING-COLUMN GUIDE BUSHING FOR R.V. GUIDE PIN a PLACES)-00 LIFT BOLT Fi gure 3: Upper Guide Structure
 
Lifting Rig (St. Lucie Unit 1 FSAR figure 9.1-8)
Attachment
 
4 IN 86-06 February 3, 1986 LIST OF RECENTLY ISSUED IE INFORMATION
 
NOTICES T nfn,'mnfi
 
n Notice No. Subject Date oT Issue T-Issud tn Issu---- --ud t 86-05 86-04 86-03 86-02 86-01 85-101 85-100 85-99 85-98 Main Steam Safety Valve Test 1/31/86 Failures And Ring Setting Adjustments
 
Transient
 
Due To Loss Of 1/31/86 Power To Integrated
 
Control System At A Pressurized
 
Water Reactor Designed By Babcock& Wilcox Potential
 
Deficiencies
 
In 1/14/86 Environmental
 
===Qualification===
Of Limitorque
 
Motor Valve Operator Wiring Failure Of Valve Operator 1/6/86 Motor During Environmental
 
Qualification
 
Testing Failure Of Main Feedwater
 
1/6/86 Check Valve Causes Loss Of Feedwater
 
System Integrity And Water-Hammer
 
Damage Applicability
 
of 10 CFR 21 12/31/85 To Consulting
 
Firms Providing Training Rosemount
 
Differential
 
12/31/85 Pressure Transmitter
 
Zero Point Shift Cracking In Boiling-Water-
12/31/85 Reactor Mark I And Mark II Containments
 
Caused By Failure Of The Inerting System All PWR facilities
 
holding an OL or CP All power reactor facilities
 
holding an OL or CP All power reactor facilities
 
holding an OL or CP All power reactor facilities
 
holding an OL or CP All power reactor facilities
 
holding an OL or CP All power reactor facilities
 
holding an OL or CP All power reactor facilities
 
holding an OL or CP All BWR facilities
 
having a Mark I or Mark II containment
 
===All Westinghouse===
designed PWR facilities
 
holding an OL or CP Missing Jumpers From Westing- 12/26/85 house Reactor Protection


==Description of Circumstances==
System Cards For The Over-Power Delta Temperature
:On November 6, 1985, while lifting the upper guide structure from the St.Lucie Unit 1 reactor vessel, licensee personnel noticed the lifting rig tilt.The lift was immediately stopped, with the lifting rig canted upward about 6inches and the guide structure canted downward about 6 inches at one of thethree attachment points. An attempt was promptly made to lower the'load backto its installed position, but the load cells indicated binding, so the attemptwas terminated after lowering the load a few inches. The 50-ton load was leftsuspended about 8 feet above the reactor core.The licensee declared an Unusual Event. Core alteration containment integritywas enhanced by resuming full use of the airlocks. Temporary primary manwaycovers were installed on bcth hot and cold legs to enhance the nozzle dams.Survey transits were set up and procedures implemented to monitor the rig andload for any shifts in their positions.The licensee and the nuclear steam system supplier, Combustion Engineering,designed and tested a supplementary lifting rig to support the upper guidestructure from the upper portion of the normal rig, using a cable and J-hooksystem. On November 9 with the supplementary rig installed, the load wasjacked to a level orientation and moved to its normal parking position in therefueling pool.8601290056 IN 86-06February 3, 1986 Damage caused during the incident included bending the lifting rig and one ofthe two guide pins that align the rig with the reactor vessel.Discussion:The upper guide structure is shown in Figure 1. It is supported in the reactorvessel by it§..upper flange. It is aligned by eight alignment keys, four at thetop and fourat the bottom. The structure fits down inside the core supportbarrel, just'above the fuel assemblies (see Figure 2). The fuel assemblyalignment plate is the bottom component of the upper guide structure.The lifting rig is attached to the upper guide structure by three verticallyoriented bolts. These bolts are attached from above the water line by torquetools that run down the hollow columns of the rig (see Figure 3). CombustionEngineering's procedure for attaching the rig calls for checking for threadengagement and torquing each bolt to 50 ft-lbs. The licensee's procedureomitted the step concerning the check for thread engagement. Subsequentinspection of the bolt that had pulled loose indicated that part of the lastthread was stripped. It is assumed that this bolt cross-threaded or bound dueto rig to guide structure misalignment during attachment and reached the 50ft-lb torque requirement with only part of one thread engaged. During thelift, the few inches of unengaged bolt shaft were pulled through the liftingrig until the bolt head rested on the rig's surface at the bottom of thecolumn, resulting in an imperceptible tilt. The resulting lateral load wasinitially s6pported by the guide pins. When the rig and guide structure werelifted about 8 feet, where the guide bushings on the lifting rig reached thetapered portion of the guide pins, it is surmised that sufficient lateralmotion was permitted to allow the thread of the improperly engaged bolt to slipfree. This caused the observed motion and tilt.After the guide structure was supported by the supplemental lifting rig andleveled, it was moved to its normal parking position in the refueling pool.The short attachment bolts and torque tools were then replaced with full-lengthbolts.- The long bolts are designed with heads that rest on surfaces at the topof the three hollow columns of the lifting rig. This has the advantage ofmaking anyflmck of full thread engagement more apparent to the personnelattaching the rig. The guide structure was subsequently returned to itsinstalled position using the long attachment bolts.The licensee has not yet decided whether to permanently modify the attachmentbolts. The licensee plans to review all reactor-related lifts for adequacy ofthe procedures to ensure proper lift rig attachment, including provisions formeasuring thread engagement.The potential consequences of dropping heavy loads into the open reactor vesselwere addressed by Unresolved Safety Issue (USI) A-36, "Control of Heavy LoadsNear Spent Fuel." The concern for a UGS drop is that fuel assemblies might besufficiently damaged to release the radioactive gases and iodines held withinthe fuel-clad gap. Under the reduced containment integrity requirements forthe refueling mode, damage to several fuel assemblies might cause the radiationdose limits of 10 CFR 100 to be exceeded.


IN 86-06February 3, 1986 Plant specific calculations were not made for a UGS drop at St. Lucie becausethe NRC determined that further calculations were not required after reviewinginitial calculations previously submitted by other reactor facilities inresponse to Phase II of USI A-36. Some indication of the consequences of aUGS drop at St. Lucie can be gained from calculations performed by CombustionEngineering for a reactor vessel head drop at Waterford 3. The head dropcalculations assumed the reactor vessel head was sufficiently tilted at impactto directly strike the UGS with the UGS at rest in its normal installed posi-tion. The calculated response velocity of the Waterford UGS was 28 feet persecond, and the resulting vertical stresses imposed on the fuel were notsufficient to rupture the cladding.If the St. Lucie UGS had dropped from an 8 foot elevation, its striking velocitywould have been substantially less than the UGS response velocity calculatedfor the Waterford head drop. However, the potential for misalignment of therecesses in the bottom of the UGS (i.e., the fuel assembly alignment plate)with the fuel assembly upper end fitting posts was not addressed by the Waterfordscenario. If substantial misalignment occurred, the fuel could be subjected toadditional axial loading. Significant misalignment could not occur withoutsubstantial impact damage to the eight keys and keyways, which would alsoresult in a reduced striking velocity of the UGS as it reached the fuel. Onthis basis, significant radioactive gas release is considered to be unlikely,although it has not been shown to be impossible.No specific action or written response is required by this notice. If youhave any questions regarding this matter, please contact the RegionalAdministrator of the appropriate NRC regional office or this office.ar Jordan, DirectorDivisio of Emergency Preparednessand gineering ResponseOffice of Inspection and EnforcementTechnical Contacts: S. M. Long, IE(301) 492-7159D. E. Sells, NRR(301) 492-9735Attachments:1. Figure 1, Upper Guide Structure Assembly2. Figure 2, Reactor Internals Assembly3 Figure 3, Upper Guide Structure Lifting Rig4. List of Recently Issued IE Information Notices
Trip Function OL = Operating


Attachment 1IN 86-06February 3, 1986EXPANSIONCOMPENSATINGRINGCEASHROUDGRIDASSEMBLY.CEA SHROUDSFUEL ASSEMBLYALIGNMENT PLATEFigure 1: Upper Guide Structure Assembly(St. Lucie Unit 1 FSAR-figure 4.2-10)
License CP = Construction
UPPER GUIDE-STRUCTURE SUPPORTPLATEAttachment 2IN 86-06February 3, 1986CEASHROUDIN-CORE-INSTRUMENTATIONGUIDE TUBEOUTLETCORE' SUPPORTBARRELFUELALIGNMENTPINSCORE-SUPPORTASSEMBLYAm. 3-7/85Figure 2: Reactor Internals Assembly(St. Lucie Unit 1 FSAR figure 4.2-7)
At ta chment3IN 86-06February 3, 1986LIFT POINT FOR CRANE HOOKCLEVIS ASSEMBLYWORKING PLATFORMI NSTRUMENTSTALK OPENING-COLUMNGUIDE BUSHING FORR.V. GUIDE PINa PLACES)-00LIFT BOLTFi gure 3:Upper Guide Structure Lifting Rig(St. Lucie Unit 1 FSAR figure 9.1-8)
Attachment 4IN 86-06February 3, 1986LIST OF RECENTLY ISSUEDIE INFORMATION NOTICEST nfn,'mnfi nNotice No. SubjectDate oTIssueT-Issud tnIssu---- --ud t86-0586-0486-0386-0286-0185-10185-10085-9985-98Main Steam Safety Valve Test 1/31/86Failures And Ring SettingAdjustmentsTransient Due To Loss Of 1/31/86Power To Integrated ControlSystem At A Pressurized WaterReactor Designed By Babcock& WilcoxPotential Deficiencies In 1/14/86Environmental QualificationOf Limitorque Motor ValveOperator WiringFailure Of Valve Operator 1/6/86Motor During EnvironmentalQualification TestingFailure Of Main Feedwater 1/6/86Check Valve Causes Loss OfFeedwater System IntegrityAnd Water-Hammer DamageApplicability of 10 CFR 21 12/31/85To Consulting Firms ProvidingTrainingRosemount Differential 12/31/85Pressure Transmitter ZeroPoint ShiftCracking In Boiling-Water- 12/31/85Reactor Mark I And Mark IIContainments Caused By FailureOf The Inerting SystemAll PWR facilitiesholding an OL orCPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll BWR facilitieshaving a Mark I orMark II containmentAll Westinghousedesigned PWRfacilities holdingan OL or CPMissing Jumpers From Westing- 12/26/85house Reactor ProtectionSystem Cards For The Over-Power Delta Temperature TripFunctionOL = Operating LicenseCP = Construction Permit


}}
Permit}}


{{Information notice-Nav}}
{{Information notice-Nav}}

Revision as of 13:01, 31 August 2018

Failure of Lifting Rig Attachment, While Lifting Upper Guide Structure at St. Lucie Unit 1
ML031220538
Person / Time
Site: Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill
Issue date: 02/03/1986
From: Jordan E L
NRC/IE
To:
References
IN-86-006, NUDOCS 8601290056
Download: ML031220538 (7)
v • d • e


SSINS No.: 6835 IN 86-06 UNITED STATES NUCLEAR REGULATORY

COMMISSION

OFFICE OF INSPECTION

AND ENFORCEMENT

WASHINGTON, D.C. 20555 February 3, 1986 IE INFORMATION

NOTICE NO. 86-06: FAILURE OF LIFTING RIG ATTACHMENT,WHILE

LIFTING THE UPPER GUIDE STRUCTURE

AT ST. LUCIE UNIT 1

Addressees

All nuclear power facilities

holding an operating

license (OL) or a construction

permit (CP). .

Purpose

This notice is provided to advise licensees

of a potentially

significant

problem that occurred during the movement of a heavy load over the reactor core. It is expected that recipients

will review this information

for applicability

to their facilities

and consider actions, if appropriate, to preclude similar problems at their facilities.

However, the suggestions

contained

in this notice do not constitute

NRC requirements;

therefore, no specific action or written response is required.Description

of Circumstances:

On November 6, 1985, while lifting the upper guide structure

from the St.Lucie Unit 1 reactor vessel, licensee personnel

noticed the lifting rig tilt.The lift was immediately

stopped, with the lifting rig canted upward about 6 inches and the guide structure

canted downward about 6 inches at one of the three attachment

points. An attempt was promptly made to lower the'load back to its installed

position, but the load cells indicated

binding, so the attempt was terminated

after lowering the load a few inches. The 50-ton load was left suspended

about 8 feet above the reactor core.The licensee declared an Unusual Event. Core alteration

containment

integrity was enhanced by resuming full use of the airlocks.

Temporary

primary manway covers were installed

on bcth hot and cold legs to enhance the nozzle dams.Survey transits were set up and procedures

implemented

to monitor the rig and load for any shifts in their positions.

The licensee and the nuclear steam system supplier, Combustion

Engineering, designed and tested a supplementary

lifting rig to support the upper guide structure

from the upper portion of the normal rig, using a cable and J-hook system. On November 9 with the supplementary

rig installed, the load was jacked to a level orientation

and moved to its normal parking position in the refueling

pool.8601290056 IN 86-06 February 3, 1986 Damage caused during the incident included bending the lifting rig and one of the two guide pins that align the rig with the reactor vessel.Discussion:

The upper guide structure

is shown in Figure 1. It is supported

in the reactor vessel by it§..upper

flange. It is aligned by eight alignment

keys, four at the top and fourat the bottom. The structure

fits down inside the core support barrel, just'above

the fuel assemblies (see Figure 2). The fuel assembly alignment

plate is the bottom component

of the upper guide structure.

The lifting rig is attached to the upper guide structure

by three vertically

oriented bolts. These bolts are attached from above the water line by torque tools that run down the hollow columns of the rig (see Figure 3). Combustion

Engineering's

procedure

for attaching

the rig calls for checking for thread engagement

and torquing each bolt to 50 ft-lbs. The licensee's

procedure omitted the step concerning

the check for thread engagement.

Subsequent

inspection

of the bolt that had pulled loose indicated

that part of the last thread was stripped.

It is assumed that this bolt cross-threaded

or bound due to rig to guide structure

misalignment

during attachment

and reached the 50 ft-lb torque requirement

with only part of one thread engaged. During the lift, the few inches of unengaged

bolt shaft were pulled through the lifting rig until the bolt head rested on the rig's surface at the bottom of the column, resulting

in an imperceptible

tilt. The resulting

lateral load was initially

s6pported

by the guide pins. When the rig and guide structure

were lifted about 8 feet, where the guide bushings on the lifting rig reached the tapered portion of the guide pins, it is surmised that sufficient

lateral motion was permitted

to allow the thread of the improperly

engaged bolt to slip free. This caused the observed motion and tilt.After the guide structure

was supported

by the supplemental

lifting rig and leveled, it was moved to its normal parking position in the refueling

pool.The short attachment

bolts and torque tools were then replaced with full-length

bolts.- The long bolts are designed with heads that rest on surfaces at the top of the three hollow columns of the lifting rig. This has the advantage

of making anyflmck of full thread engagement

more apparent to the personnel attaching

the rig. The guide structure

was subsequently

returned to its installed

position using the long attachment

bolts.The licensee has not yet decided whether to permanently

modify the attachment

bolts. The licensee plans to review all reactor-related

lifts for adequacy of the procedures

to ensure proper lift rig attachment, including

provisions

for measuring

thread engagement.

The potential

consequences

of dropping heavy loads into the open reactor vessel were addressed

by Unresolved

Safety Issue (USI) A-36, "Control of Heavy Loads Near Spent Fuel." The concern for a UGS drop is that fuel assemblies

might be sufficiently

damaged to release the radioactive

gases and iodines held within the fuel-clad

gap. Under the reduced containment

integrity

requirements

for the refueling

mode, damage to several fuel assemblies

might cause the radiation dose limits of 10 CFR 100 to be exceeded.

IN 86-06 February 3, 1986 Plant specific calculations

were not made for a UGS drop at St. Lucie because the NRC determined

that further calculations

were not required after reviewing initial calculations

previously

submitted

by other reactor facilities

in response to Phase II of USI A-36. Some indication

of the consequences

of a UGS drop at St. Lucie can be gained from calculations

performed

by Combustion

Engineering

for a reactor vessel head drop at Waterford

3. The head drop calculations

assumed the reactor vessel head was sufficiently

tilted at impact to directly strike the UGS with the UGS at rest in its normal installed

posi-tion. The calculated

response velocity of the Waterford

UGS was 28 feet per second, and the resulting

vertical stresses imposed on the fuel were not sufficient

to rupture the cladding.If the St. Lucie UGS had dropped from an 8 foot elevation, its striking velocity would have been substantially

less than the UGS response velocity calculated

for the Waterford

head drop. However, the potential

for misalignment

of the recesses in the bottom of the UGS (i.e., the fuel assembly alignment

plate)with the fuel assembly upper end fitting posts was not addressed

by the Waterford scenario.

If substantial

misalignment

occurred, the fuel could be subjected

to additional

axial loading. Significant

misalignment

could not occur without substantial

impact damage to the eight keys and keyways, which would also result in a reduced striking velocity of the UGS as it reached the fuel. On this basis, significant

radioactive

gas release is considered

to be unlikely, although it has not been shown to be impossible.

No specific action or written response is required by this notice. If you have any questions

regarding

this matter, please contact the Regional Administrator

of the appropriate

NRC regional office or this office.ar Jordan, Director Divisio of Emergency

Preparedness

and gineering

Response Office of Inspection

and Enforcement

Technical

Contacts:

S. M. Long, IE (301) 492-7159 D. E. Sells, NRR (301) 492-9735 Attachments:

1. Figure 1, Upper Guide Structure

Assembly 2. Figure 2, Reactor Internals

Assembly 3 Figure 3, Upper Guide Structure

Lifting Rig 4. List of Recently Issued IE Information

Notices

Attachment

1 IN 86-06 February 3, 1986 EXPANSION COMPENSATING

RING CEA SHROUD GRID ASSEMBLY.CEA SHROUDS FUEL ASSEMBLY ALIGNMENT

PLATE Figure 1: Upper Guide Structure

Assembly (St. Lucie Unit 1 FSAR-figure

4.2-10)

UPPER GUIDE-STRUCTURE

SUPPORT PLATE Attachment

2 IN 86-06 February 3, 1986 CEA SHROUD IN-CORE-INSTRUMENTATION

GUIDE TUBE OUTLET CORE' SUPPORT BARREL FUEL ALIGNMENT PINS CORE-SUPPORT ASSEMBLY Am. 3-7/85 Figure 2: Reactor Internals

Assembly (St. Lucie Unit 1 FSAR figure 4.2-7)

At ta chment3 IN 86-06 February 3, 1986 LIFT POINT FOR CRANE HOOK CLEVIS ASSEMBLY WORKING PLATFORM I NSTRUMENT STALK OPENING-COLUMN GUIDE BUSHING FOR R.V. GUIDE PIN a PLACES)-00 LIFT BOLT Fi gure 3: Upper Guide Structure

Lifting Rig (St. Lucie Unit 1 FSAR figure 9.1-8)

Attachment

4 IN 86-06 February 3, 1986 LIST OF RECENTLY ISSUED IE INFORMATION

NOTICES T nfn,'mnfi

n Notice No. Subject Date oT Issue T-Issud tn Issu---- --ud t 86-05 86-04 86-03 86-02 86-01 85-101 85-100 85-99 85-98 Main Steam Safety Valve Test 1/31/86 Failures And Ring Setting Adjustments

Transient

Due To Loss Of 1/31/86 Power To Integrated

Control System At A Pressurized

Water Reactor Designed By Babcock& Wilcox Potential

Deficiencies

In 1/14/86 Environmental

Qualification

Of Limitorque

Motor Valve Operator Wiring Failure Of Valve Operator 1/6/86 Motor During Environmental

Qualification

Testing Failure Of Main Feedwater

1/6/86 Check Valve Causes Loss Of Feedwater

System Integrity And Water-Hammer

Damage Applicability

of 10 CFR 21 12/31/85 To Consulting

Firms Providing Training Rosemount

Differential

12/31/85 Pressure Transmitter

Zero Point Shift Cracking In Boiling-Water-

12/31/85 Reactor Mark I And Mark II Containments

Caused By Failure Of The Inerting System All PWR facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All BWR facilities

having a Mark I or Mark II containment

All Westinghouse

designed PWR facilities

holding an OL or CP Missing Jumpers From Westing- 12/26/85 house Reactor Protection

System Cards For The Over-Power Delta Temperature

Trip Function OL = Operating

License CP = Construction

Permit


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