Information Notice 1985-84, Inadequate Inservice Testing of Main Steam Isolation Valves

Inadequate Inservice Testing of Main Steam Isolation Valves

ML031180213
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:	10/30/1985
From:	Jordan E NRC/IE
To:
References
IN-85-084, NUDOCS 8510250546
Download: ML031180213 (4)

SSINS No.: 6835 IN 85-84

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C.

20555

October 30, 1985

IE INFORMATION NOTICE NO. 85-84:

INADEQUATE INSERVICE TESTING OF MAIN STEAM

ISOLATION VALVES

Addressees

All nuclear power reactor facilities holding an operating license (OL) or a

construction permit (CP).

Purpose

This notice is being provided to alert recipients of a potentially significant

problem concerning the possible failure of main steam isolation valves (MSIVs)

to close under low steam flow conditions and the testing of these valves with

non-safety-related motive power in place.

It is expected that recipients will

review the information for applicability to their facilities and consider

actions, if appropriate, to preclude a similar problem 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.

Past Related Correspondence

Information Notice 85-21, "Main Steam Isolation Valve Closure Logic", March 18,

1985.

Description of Circumstances

During inspections at Robinson Unit 2 in November 1984 and at Turkey Point

Units 3 and 4 in February 1985, NRC inspectors noted that MSIV surveillance

testing procedures did not call for securing the instrument air supply to the

MSIV control system during a test.

Recognizing this as contrary to the objec- tive of operational verification of the MSIVs, the NRC cited these plants for

violating 10 CFR 50.55a(g).

After reviewing the matter to determine the corrective action, Florida Power &

Light Co., the licensee for Turkey Point Units 3 and 4, reported to the NRC on

July 23, 1985, that a deficiency existed concerning the ability of MSIVs to

close under low steam flow conditions.

The safety-related air supply, stored

in accumulators, was not adequate to close the valves in the event of loss of

the non-safety-related instrument air system.

This had not been discovered

during routine testing because that testing had been performed improperly using

the non-safety-related instrument air to achieve closure.

8510250546

J

IN 85-84 October 30, 1985 Operating air for the MSIVs is stored in accumulators mounted on the valve

assembly; the non-safety-related plant instrument air system provides addition- al supply.

During normal operation the MSIVs at Turkey Point are held open

against steam flow by air pressure acting on the bottom of the actuator operat- ing piston.

When a closing signal is received, air is directed to the top of

the piston while air is vented from the bottom of the piston.

Closure of each

MSIV is assisted by a spring that moves the piston part way, by steam flow in

the steam line, and by gravity. Assuming a loss of the instrument air system, the air stored in the safety-related accumulators may not be adequate to close

the MSIV without sufficient assistance from steam flow.

The Turkey Point MSIVs are required to close within 5 seconds to mitigate the

consequences of a large main steam line break accident.

In the event of such

an accident, the high steam flow rate would assist in closing the MSIVs.

However, MSIV closure also is required for other events in which large steam

flow may not exist.

Under these conditions and a loss of instrument air

pressure, the accumulator air volume may not be sufficient to close the MSIVs.

In the regulations, 10 CFR 50.55a(g) requires that inservice testing to verify

operational readiness of pumps and valves whose function is required for safety

be accomplished in accordance with Section XI of the ASME Boiler and Pressure

Vessel (BPV) Code.

The ASME BPV Code,Section XI, 1980 edition through winter

1980 addenda, Paragraph IWV-3415Srequires-that-fail-safe valves be testedLby -

observing the operation of the valves upon loss of actuator power.

Since the

MSIVs have been identified as fail-safe valves they should have been tested

with the instrument air supply, as well as electric power, removed.

Proper

testing would have revealed the inadequate accumulators much earlier.

Discussion:

The practice of performing inservice testing of components, which are relied on

to mitigate the consequences of accidents, with sources of power not considered

in the safety analyses is not in keeping with the objective of.periodic test- ing.

This objective is to test equipment to verify operational readiness under

conditions that reasonably duplicate the design basis. When such testing was

performed at Turkey Point, it was shown that with low or no steam flow, MSIV

closure could only be assured with instrument air powering the actuator.

Continued operation at Turkey Point has been justified by the availability of

two instrument air systems as backups and by procedures that require plant

shutdown if the instrument air supply is lost.

In addition, design modifica- tions are being implemented on an expedited basis that will ensure MSIV closure

in 5 seconds without steam flow assistance or non-safety-related instrument air

power.

These modifications also will resolve the testing deficiency noted

above.

IN 85-84 October 30, 1985 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.

4i~~4/4rdan, Dire~ctor

Division

Emergency Preparedness

and Engineering Response

Vern Hodge, IE

(301) 492-7275 Attachment: List of Recently Issued IE Information Notices

Attachment 1

IN 85-84

October 30, 1985

LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issue

Issued to

85-83 Potential Failures Of General 10/30/85 Electric PK-2 Test Blocks

85-82

85-81

85-80

85-17 Sup. 1 Diesel Generator Differen- tial Protection Relay Not

Seismically Qualified

Problems Resulting In

Erroneously High Reading

With Panasonic 800 Series

Thermoluminescent Dosimeters

Timely Declaration Of An

Emergency Class Implementa- tion Of An Emergency Plan,

And Emergency Notifications

Possible Sticking Of ASCO

Solenoid Valves

Inadequate Communications

Between Maintenance,

Operations, And Security

Personnel

Event Notification

Possible Loss Of Emergency

Notification System Due To

Loss Of AC Power

10/18/85

1

10/17/85

10/15/85

10/1/85

9/30/85

9/23/85

9/20/85

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 and

certain material

and fuel cycle

licensees

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; research

and nonpower reactor

facilities; fuel

fabrication and

processing facilities

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

85-79

85-78 f.

85-77 OL = Operating License

CP = Construction Permit