Information Notice 1996-12, Control Rod Insertion Problems

Control Rod Insertion Problems

ML031060255
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, 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, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	02/15/1996
From:	Crutchfield D Office of Nuclear Reactor Regulation
To:
References
IN-96-012, NUDOCS 9602090161
Download: ML031060255 (10)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001 February 15, 1996 NRC INFORMATION NOTICE 96-12: CONTROL ROD INSERTION PROBLEMS

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

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

notice to alert addressees to recent events during which rod control cluster

assemblies failed to insert fully. It is expected that recipients will 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

South Texas Project

On December 18, 1995, with South Texas Unit 1 at 100 percent power, a pilot

wire monitoring relay actuation caused a main transformer lock out which

resulted in a turbine trip and reactor trip. While verifying that control

rods had inserted fully after the trip, operators noted that the rod bottom

lights of three control rod assemblies were not lit; the digital rod position

indication for each rod indicated six steps withdrawn. Boration of the

reactor coolant system was occurring with the charging pump suction having

been transferred to the refueling water storage tank. One rod did drift into

the fully inserted rod bottom position within one hour, and the other two rods

were manually inserted later. During subsequent testing of all control rods

in the affected banks, the rod position indication for the same three

locations as well as a new location indicated six steps withdrawn. As

compared to prior rod drop testing, no significant differences in rod drop

times were noted before reaching the upper dashpot area for any of the control

rods. Within an hour after the rod drop tests, two of the rods drifted to rod

bottom position and the other two were manually inserted. All four control

rods were located in fuel assemblies that were in their third cycle with

burnup greater then 42,880 megawatt days(MWD)/metric ton uranium(MTU).

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9602090161  ;

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IN 96-12 February 15, 1996 Wolf Creek

from 80-percent power, five control

On January 30, 1996, after a manual scram insert fully. Two rods remained'at six

rod assemblies at Wolf Creek failed to one at 18 steps. Three of the affected

steps withdrawn, two at 12 steps, and

20 minutes, one within 60 minutes, and

rods drifted to fully inserted within the scram, the licensee initiated

the last one within 78 minutes. After all rods did not insert fully. The

emergency boration, as required, becausefuel with burnup greater than

five rods were all in 17x17 VANTAGE 5H

47,000 MWD/MTU.

Discussion

fuel length core design is used.

At both South Texas units, a 14-foot active 12-foot active fuel design and the

Several differences between the standard fuel design is approximately 76.2 cm

14-foot one are as follows: the 14-foot assembly design, it has 10 mid grids

[30 inches] longer than the standard fuel25.4 cm [10 inches] longer and

compared to 8 and the dashpot region is rod radial clearances above and in

comprises a double dashpot. The controlassembly are similar to those of the

the dashpot region of the 14-foot fuel contains three different 17x17 fuel

standard design. The South Texas core VANTAGE 5H--all of which are designed

types--Standard XL, Standard XLR, and was the first operating cycle with

and fabricated by Westinghouse. This 57 silver-indium-cadmium rods. The

VANTAGE 5H fuel. The core also contains Standard XLR fuel assemblies.

four affected rods were found in twice-burned

traces revealed no significant change

During subsequent testing, the rod drop rods did not show recoil on the

in dashpot entry time; however, the affected

affect that is normally seen in the

rod drop trace. Recoil is a dampening hub spring contact against the fuel

traces due to control rod assembly spiderwere tested, the results revealed no

assembly. When similar rods in Unit 2 the "no recoil" effect but inserted

adverse indications. One rod did show

fully into the core.

testing of all of the control rod

At Wolf Creek, subsequent cold, full flowrods, including the five control rods

assemblies indicated that eight control January 30, 1996, reactor trip, did

that did not fully insert following the rod, H2, paused at 96 steps, not fully insert when tripped. One control to 30 steps over the next 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

stopped at 90 steps, and slowly inserted The 7 other affected rods stopped

The control rod was then manually inserted.5 of which fully inserted within

at various heights in the dashpot region, to the bottom within one and a half

22 minutes. One of the other two driftedbe manually inserted. The remaining

hours while the remaining rod needed to a number of the rods did not

45 rods fully inserted when dropped, although

Of the total 53 control rod

exhibit the expected number of recoils. the dashpot region) is a hafnium

assemblies, H2 (thie only rod slowing outside control rod

control rod, while the remaining are silver-indium-cadmium

rods that stuck, as well as those rods

assemblies. The licensee retested all and the results were similar to the

that failed to recoil more than twice, previous testing.

I

IN 96-12 February 15, 1996 Westinghouse, Westinghouse Owners Group, and the respective licensees are

pursuing the root cause identification of these events. Possible root causes

are as follows: debris (foreign matter), control rod or drive line

degradation, corrosion products, thimble tube bow, fuel assembly bow and/or

twist, reduction in thimble tube diameter, adverse alignment of guide tube

cards, and/or design tolerances.

Some foreign reactors have also experienced slow and/or stuck control rod

assemblies.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation project manager.

a or

Division of Reactor P gram Management

Office of Nuclear Reactor Regulation

Technical contacts: Margaret Chatterton, NRR

(301) 415-2889 Internet: msc1@nrc.gov

Stephen Koenick, NRR

(301) 415-2841 Internet: ssk2@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

K>

Attachment

IN 96-12 February 15, 1996 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

96-11 Ingress of Demineralizer 02/14/96 All holders of OLs or CPs

Resins Increases Potential for pressurized water

Stress Corrosion Cracking nuclear power reactors

of Control Rod Drive

Mechanism Penetrations

96-10 Potential Blockage by 02/13/96 All holders of OLs or CPs

Debris of Safety System for nuclear power reactors

Piping Which is Not Used

During Normal Operation

or Tested During Surveil- lances

96-09 Damage in Foreign Steam 02/12/96 All holders of OLs or CPs

Generator Internals for pressurized water

reactors

96-08 Thermally Induced Pres- 02/05/96 All holders of OLs or CPs

sure Locking of a High for nuclear power reactors

Pressure Coolant Injec- tion Gate Valve

96-07 Slow Five Percent Scram 01/26/96 All holders of OLs or CPs

Insertion Times Caused for boiling water reactors

By Viton Diaphragms in

Scram Solenoid Pilot

Valves

96-06 Design and Testing 01/25/96 All holders of OLs or CPs

Deficiencies of Tornado for nuclear power reactors

Dampers at Nuclear Power

Plants

96-05 Partial Bypass of Shutdown 01/18/96 All holders of OLs or CPs

Cooling Flow from the for boiling water reactors

Reactor Vessel

96-04 Incident Reporting Require- 01/10/96 All radiography licensees

ments for Radiography and manufacturers of radio- Licensees graphy equipment

OL = Operating License

CP = Construction Permit

IN 96-12 February 15, 1996 Westinghouse, Westinghouse Owners Group, and the respective licensees are

pursuing the root cause identification of these events. Possible root causes

are as follows: debris (foreign matter), control rod or drive line

degradation, corrosion products, thimble tube bow, fuel assembly bow and/or

twist, reduction in thimble tube diameter, adverse alignment of guide tube

cards, and/or design tolerances.

Some foreign reactors have also experienced slow and/or stuck control rod

assemblies.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation project manager.

original signed by

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Margaret Chatterton, NRR

(301) 415-2889 Internet: mscl@nrc.gov

Stephen Koenick, NRR

(301) 415-2841 Internet: ssk2@nrc.gov

Reviewed and concurred on by tech editor 02/01/96 *SEE PREVIOUS

CONCURRENCES

DOCUMENT NAME: 96-12.IN

To receive a copy of this document, Indicate in the box: 'C' = Copy without enclosures 'E'

IOFFICE ITECH CONTS I IC:SPLB I

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NAME MChatterton* RJones* AChaffee

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IN 96-xx

February xx, 1996 hafnium control rod, while the remaining are silver-indium-cadmium RCCAs. toThe

licensee retested all rods that stuck, as well as those rods that failed

recoil more than twice, and the results were similar to the previous testing.

Some foreign reactors have also experienced slow and/or stuck RCCAs.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation project manager.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Margaret Chatterton, NRR

(301) 415-2889 Internet: mscl~nrc.gov

Stephen Koenick, NRR

(301) 415-2841 Internet: ssk2@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

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February xx, 1996 hafnium control rod, while the remaining are silver-indium-cadmium RCCAs. The

licensee retested all rods that stuck, as well as those rods that failed to

recoil more than twice, and the results were similar to the previous testing.

Some foreign reactors have also experienced slow and/or stuck RCCAs.

This Information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation project manager.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Margaret Chatterton, NRR

(301) 415-2889 Internet: mscl@nrc.gov

Stephen Koenick, NRR

(301) 415-2841 Internet: ssk2@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:\IN\IN ST CR.SSK

OFFICE PECB/DRPM I SPLB /DSSA ADM:PUB I SC:SPLBDSSA 1 RIVDRS

NAME SKoenick* MChatterton* TECH ED* EWeiss*

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February xx, 1996 rods did not exhibit the expected number of recoils. The licensee retested

all rods that stuck, as well as those rods that failed to recoil more than

twice, and the results were similar to the previous testing.

Some foreign reactors have also experienced of slow and/or stuck RCCAs.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation project manager.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Margaret Chatterton, NRR

(301) 415-2889 Internet: mscltnrc.gov

Stephen Koenick, NRR

(301) 415-2841 Internet: ssk2@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

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February xx, 1996 Some foreign reactors have also experienced of slow and/or stuck RCCAs.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation project manager.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Margaret Chatterton, NRR

(301) 415-2889 Internet: msclnrc.gov

Stephen Koenick, NRR

(301) 415-2841 Internet: ssk2@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

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Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts:

Stephen Koenick, NRR

(301) 415-2841

/_ Internet: ssk2@nrc.gov

Attachment:

List of Recently Issued NRC Information Notices

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