Information Notice 1986-82, Failures of Scram Discharge Volume Vent and Drain Valves

Failures of Scram Discharge Volume Vent and Drain Valves

ML031250229
Person / Time
Issue date:	09/16/1986
From:	Jordan E NRC/IE
To:
References
IN-86-082, NUDOCS 8607110321
Download: ML031250229 (3)

SSINS No.: 6835 IN 86-82 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 September 16, 1986 IE INFORMATION NOTICE NO. 86-82: FAILURES OF SCRAM DISCHARGE VOLUME VENT AND

DRAIN VALVES

Addressees

All nuclear power reactor facilitiesholding an operating license or a con- struction permit.

Purpose

This notice is provided to inform recipients of a potentially significant problem

pertaining to failures of the Hammel-Dahl valves used as vent and drain valves

in the control rod drive (CRD) systems of certain boiling water reactors. It is

suggested that recipients will review the information for applicability to their

facilities and consider actions, if appropriate, to preclude a similar problem

from 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

On February 8, 1985, the General Electric Company (GE) notified the NRC of a

coupling failure of the 2"-2500# Hammel-Dahl valve used as a CRD drain valve

in the scram discharge volume (SDV). The coupling connected the air actuator

to the valve stem and its failure prevented the valve from fully opening or

closing. This failure had occurred during equipment qualification in a labor- atory and was due to automatic actuation while the manual handwheel was parti- ally engaged.

GE identified the 2"-600#, 1"-2500#, and 1"-600# as having the same coupling

design. The 1" valves are used as SOV vent valves.

On May 13,1985, GE issued service information letter (SIL) 422 to inform its

customers of the potential for failure of the valve and recommended actions.

In SIL 422, GE mentions a related problem that occurred at an operating plant.

Subsequently, two additional operating plants have experienced valve failures

caused by partially engaged handwheels: Limerick in November of 1985 and Hope

Creek in May of 1986. Limerick found an SDV drain valve with its handwheel off

the neutral position and attempted to actuate the valve from the control room.

The valve would not operate. Hope Creek found a coupling failed in a drain

valve and the handwheel partially engaged.

8607110321

i

IN 86-82 September 16, 1986 Discussion:

The SDV vent and drain valves are primary containment isolation valves that are

normally open while the plant is operating. There are two valves in series in

each vent and drain line. They allow water from the normal CRD seal leakage to

drain to radwaste rather than accumulate in the SDV. When a scram occurs, the

vent and drain valves close to isolate reactor coolant from radwaste.

GE SIL 422 recommends that licensees "provide adequate training, operating

procedures, and checks to help assure that the handwheels of the valves are in

the neutral position to prevent inadvertent engagement of the handwheel during

automatic actuation of the valves."

When the handwheel is engaged or partially engaged, the automatic actuation

function may be prevented, or, if it occurs, may damage the actuator or stem of

the valve, causing it to fail in its "as-is" position. These valves are primary

containment isolation valves. If two valves in series fail open, a discharge

path will exist for reactor coolant to drain to the plant drain system. This

path can be isolated by resetting the scram signal or by manually closing the

1. 102 or #112 valves on each associated hydraulic control unit (HCU). (There are

approximately 92 HCUs per SDV.) If the vent and drain valves fail closed, the

CRD seal leakage will collect in the SDV until the SDV level reaches the scram

set point.

The failure of either redundant vent valve and or either redundant drain valve

represent a degradation of safety systems (CRD, primary containment, and the

primary containment isolation system) and could result in unnecessary challenges

of the reactor protection system. Licensee corrective actions have included

training, procedure revision, and enhanced surveillance as well as adding

administrative controls to maintain the handwheels in the neutral position.

No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the Regional

Administrator of the appropriate regional office or this office.

d-w // o Z or

Divisi of Emergency Preparedness

and gineering Response

Office of Inspection and Enforcement

Mary S. Wegner, IE

(301)492-4511 Attachment: List of Recently Issued IE Information Notices

Attachment 1 IN 86-82 September 16, 1986 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

86-81 Broken Inner-External Closure 9/15/86 All power reactor

Springs On Atwood & Morrill facilities holding

Main Steam Isolation Valves an OL or CP

86-80 Unit Startup With Degraded 9/12/86 All power reactor

High Pressure Safety Injection facilities holding

System an OL or CP

86-79 Degradation Or Loss Of 9/2/86 All power reactor

Charging Systems At PWR facilities holding

Nuclear Power Plants Using an OL or CP

Swing-Pump Designs

86-78 Scram Solenoid Pilot Valve 9/2/86 All BWR facilities

(SSPV) Rebuild Kit Problems holding an OL or CP

86-77 Computer Program Error Report 8/28/86 All power reactor

Handling facilities holding

an OL or CP and

nuclear fuel man- ufacturing facilities

86-76 Problems Noted In Control 8/28/86 All power reactor

Room Emergency Ventilation facilities holding

Systems an OL or CP

86-75 Incorrect Maintenance 8/21/86 All power reactor

Procedure On Traversing facilities holding

Incore Probe Lines an OL or CP

86-74 Reduction Of Reactor Coolant 8/20/86 All BWR facilities

Inventory Because Of Misalign- holding an OL or CP

ment Of RHR Valves

86-73 Recent Emergency Diesel 8/20/86 All power reactor

Generator Problems facilities holding

an OL or CP

86-72 Failure 17-7 PH Stainless 8/19/86 -All power reactor

Steel Springs In Valcor facilities holding

Valves Due to Hydrogen an OL or CP

Embrittlement

OL = Operating License

CP = Construction Permit