Information Notice 1986-68, Stuck Control Rod

Stuck Control Rod

ML031250095
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:	08/15/1986
From:	Jordan E NRC/IE
To:
References
IN-86-068, NUDOCS 8608130205
Download: ML031250095 (3)

SSINS No.: 6835 IN 86-68 UNITED STATES NUCLEAR REGULATORY

COMMISSION

OFFICE OF INSPECTION

AND ENFORCEMENT

WASHINGTON, D.C. 20555 August 15, 1986 IE INFORMATION

NOTICE NO. 86-68: STUCK CONTROL ROD

Addressees

All boiling water reactor facilities

holding an operating

license or a construction

permit.

Purpose

This notice alerts addressees

to the potential

for a stuck control rod and damaged control rod drive as a result of closed manual isolation

valves on the hydraulic

control unit. Recipients

are expected to review the information

for applicability

to their facilities

and consider actions, if appropriate, to preclude similar problems 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:

During a full scram preoperational

test (before fuel loading) on April 29, 1986, the Clinton nuclear power plant found that rod 08-25 was stuck at position 06.Attempts to move the rod by gradually

increasing

drive water pressure were unsuccessful.

Investigation

revealed that the 112 valve (scram discharge

riser manual isolation)

on the hydraulic

control unit was in the closed position despite verification

that the valve was in the proper (open) position.

The closed 112 valve caused a very high pressure to develop in the control rod drive, crushing the cylinder tube. Because the surface area above the piston is smaller than that below the piston, a closed 112 valve can cause pressures

above the piston to be several times as large as the 1850 psi applied at the bottom of the piston by the scrm accumulators.

The above-the-piston

water surrounds

the cylinder and can partially crush the cylinder.

The crushed cylinder tube caused interference

with the movement of the piston and thus the stuck rod.Subsequent

unsuccessful

attempts were made to insert the partially

withdrawn control rod into its drive by removing temporary

blade guide assemblies

and applying force from above with a specially

constructed

tool. The rod was ultimately

removed by cutting the index tube into two pieces and removing.

it from the drained reactor vessel.if_., -eff C

IN 86-68 August 15, 1986 The licensee has adopted a number of corrective

measures.

The manual isolation valves are locked open once they are verified to be in the proper position.The personnel

access control to the hydraulic

control units has been tightened.

In addition to the normal independent

verification

of valve position, the start-up organization

has instituted

a temporary

measure of having management

personnel

make additional

random checks.Discussion:

Although not always causing damage to the control rod drive as occurred at Clinton, there have been several instances

of manual isolation

valves on the hydraulic

control units causing failure to scram of individual

control rods.Among the other instances

when problems with the manual isolation

valves on the hydraulic

control unit have prevented

a rod from scraming are: Date Plant Event-Failure

to Scram One Rod October 20, 1984 Dresden Unit 3 Manual isolation

valve disc separated

from valve stem October 24, 1984 Quad Cities Unit 2 Scram inlet isolation

valve closed April 11, 1985 Perry Inadvertently

closed 112 valve -CRDM damaged, index tube cut to remove There are other valves on the hydraulic

control unit that could prevent a scram or cause damage to the control rod drive mechanism.

Some of these valves could be discovered

by problems with normal rod movement before a scram. However, a closed 112 valve does not cause problems with normal rod movement.

Because larger pressures

are applied to the control rod drive during the scram, damage caused by closed valves on the hydraulic

control unit is most likely to occur during the scram.No specific action or written response is required by this information

notice.If you have questions

about this matter, please contact the Regional Adminis-trator of the appropriate

NRC regional office or this office.ard Jordan, Director Divisi of Emergency

Preparedness

and Engineering

Response Office of Inspection

and Enforcement

Technical

Contact: Eric Weiss, IE (301) 492-9005 Attachment:

List of Recently Issued IE Information

Notices

Attachment

1 IN 86-68 August 15, 1986 LIST OF RECENTLY ISSUED IE INFORMATION

NOTICES Information

Date of Notice No. Subject Issue Issued to 86-67 86-66 86-65 86-64 86-63 86-62 86-61 86-60 86-31 Sup. 1 Portable Moisture/Density

8/15/86 Gauges: Recent Incidents

And Common Violations

Of Require-ments For Use, Transportation, And Storage Potential

For Failure Of 8/15/86 Replacement

AC Coils Supplied By The Westinghouse

Electric Corporation

For Use In Class lE Motor Starters And Contractors

Malfunctions

Of ITT Barton 8/14/86 Model 580 Series Switches During Requalification

Testing Deficiencies

In Upgrade 8/14/86 Programs For Plant Emergency Operating

Procedures

Loss Of Safety Injection

8/6/86 Capability

Potential

Problems In West- 7/31/86 inghouse Molded Case Circuit Breakers Equipped With A Shunt Trip Failure Of Auxiliary

Feed- 7/28/86 water Manual Isolated Valve Unanalyzed

Post-LOCA

Release 7/28/86 Paths Unauthorized

Transfer And 7/14/86 Loss Of Control Of Industrial

Nuclear Gauges All NRC licensees authorized

to possess, use, transport, and store sealed sources 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 PWR facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All power reactor facilities

holding a CP All power reactor facilities

holding an OL or CP All NRC general licensees

that possess and use industrial

nuclear gauges OL = Operating

License CP = Construction

Permit