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, 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, Crane
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:

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

Eric Weiss, IE

(301) 492-9005 Attachment:

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