Information Notice 1988-68, Setpoint Testing of Pressurizer Safety Valves with Filled Loop Seals Using Hydraulic Assist Devices

Setpoint Testing of Pressurizer Safety Valves with Filled Loop Seals Using Hydraulic Assist Devices

ML031150163
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
Issue date:	08/22/1988
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-88-068, NUDOCS 8808160451
Download: ML031150163 (6)

UNITED STATES

NUCLEAR REGULATORY CQOMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 August 22, 1988 NRC INFORMATION NOTICE NO. 88-68: SETPOINT TESTING OF PRESSURIZER SAFETY

VALVES WITH FILLED LOOP SEALS USING

HYDRAULIC ASSIST DEVICES

Addressees

permits for nuclear power

All holders of operating licenses or construction

reactors.

Purpose

to alert addressees to potentially

This information notice is being provided testing of pressurizer safety valves

generic problems that have occurred duringassist device. Use of hydraulic

with filled loop seals using a hydraulic results for safety valve setpoint

assist devices may result in inaccurateto water or two-phase flow. It is

testing when the valves are subjected information for applicability to their

expected that recipients will review the

facilities and consider actions, asthisappropriate. to avoid similar problems.

notice do not constitute NRC require- However, suggestions contained in written response is required.

ments; therefore, no specific action or

Description of Circumstances

Canyon 1 tested the three pressur- On August 30, 1986, the licensee of Diablo using a hydraulic assist device.

izer safety valves with the loop seal filled

as 2747.8, 3028.0, and 2661.0 psig for

The initial lift points were reported respectively. The required setpoint for

valves number RCS-1-8010A, B, and C, method monitored hydraulic pressure on

the valves was 2485+/-1% psig. The test stem displacement to infer lift point.

the test rig for an indication of valve lift point was not accurate on the

The licensee concluded that the inferred drained. Water moving through the

first lift because the loop seal was not because of the different

seat area produced little valve stem displacement then entered the valves at an

physical properties of steam and water. Steam displacement, resulting in the

elevated hydraulic pressure and caused a larger After the loop seal was

point.

prediction of an inaccurately high lift were

points of the valves measured again and found to be

drained, the lift

(2485+/-1%) at 2464, 2493, and 2503 within technical specification (TS) limits

psig (LER 50/275-86/018).

2 tested the setpoints of the

On April 2, 1988, the licensee of Sequoyah low setpoints could be the cause of

pressurizer safety valves to determine if A hydraulic assist device

the leakage that the valves had been experiencing.

a80451 s

IN 88-68 August 22, 1988 was used with reactor pressure between 1700 psig and normal operating pressure, and with a water seal at the valve seat maintained at an elevated temperature

by external heaters. The lifting force required to open the valve was measured

by a load cell and recorded on a strip chart to provide data necessary to

calculate the valve setpoint. Disc lift was determined by a change in slope on

the load cell trace and confirmed by test personnel who listened for audible

passage of flow through the discharge piping. With valve lift assumed known, the lift force was used to calculate an equivalent pressure. This pressure was

added to the system static pressure to infer the valve setpoint. Initial lift

results were 2634 psig for valve 2-68-563, 2678 psig for 2-68-564, and 2660

psig for 2-68-565. The required setpoint was 2485+/-1% psig for each valve.

Setpoints were readjusted and the valves were retested in situ, after re- establishing the water seal.

On April 8, 1988, with the unit in cold shutdown, the Sequoyah 2 pressurizer

safety valves were sent to Wyle Laboratories for bench testing and seat refur- bishment. The valve lifts were performed using water heated to 1200F and

pressurized by nitrogen. Valve stem lift was directly measured by a linear

voltage differential transformer (LVDT) mounted on the valve stem, and the stem

displacement was recorded on a strip chart. The lift setting was indicated by

a clear peak on the pressure strip chart and confirmed by spindle displacement

measured by the LVDT. Two of the valves had some internal parts replaced prior

to the tests. Lift points were 2435 and 2384 psig for valve 2-68-563, 2430 and

2432 psig for 2-68-564, and 2390 psig for 2-68-565.

The different lift points of the Sequoyah 2 valves were attributed to differ- ences in determining the time at which the disc began to lift. The LVDT used

at Wyle was accurate to 0.001 inch. The licensee's in situ method used a

change in the slope of a trace of lift force on a strip chart, backed up by

technicians' confirmation of audible flow.

The licensee found that the setpoint adjustments made as a result of the

Sequoyah 2 in situ tests brought the setpoint of the valves outside the limits

of the TS. This situation could have resulted in the premature liftina of the

safety valves (LER 50/328-88/016).

The licensee for Diablo Canyon has decided to drain the pressurizer safety

valve loop seal before testing. The licensee for Sequoyah is planning to send

pressurizer safety valves to Wyle Laboratories for future testing.

Hydraulic assist devices have been shown to be accurate in testing spring- actuated safety valve setpoints with saturated steam as the lift medium. They

have not been shown to be accurate for safety valve setpoint testing using

water or two-phase flow. The results of the Diablo Canyon 1 and Sequoyah 2 tests appear to show that these devices produce inaccurate results when testing

pressurizer safety valves with filled loop seals. If the inaccurate results

are believed and the valves are reset, a situation can occur in which the

setpoints of the valves are low, resulting in valve leakage, and/or premature

lift.

iN 88-68 August 22, 1988 No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact one of the techni- cal contacts listed below or the Regional Administrator of the appropriate NRC

regional office.

rles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Mary S. Wegner, AEOD

(301) 492-7818 Charles G. Hammer, NRR

(301) 492-0919 Attachment: List of Recently Issued NRC Information Notices

Attachment

IN 88-68 August Z2. 19E8 Page I of I

.ILIST OF RECENTLY ISSUED

NRC INFCRI'ATION NOTICES

InTorratiOn

I'l forr atixon Date of

INotice No. Subject Issuance Issued to

I88-67 PWR Auxiliary Feedwater Pump 8/22/Ea All nolders of Os

Turbine Overspeed Trip or CFs for nuclear

Failure power reactors.

88-66 Industrial Padicgracty 8/22/6E All NRCinoustrial

Inspection and Enfcrcement radiOcraphy licensees.

88-65 Iracyertent Drainaces of 8/18/e8 All holders of OLs

Spent Fuel Peols or CPs for nuclear

power reactors aro

fuel storace facilities.

88-64 Recorting Fires in Nuclear 8/1e/88 All holders of ^Ls

Process Systems at; Nuclear or CPs for nuc eer

Power Plants power reactors.

88-E3 huigh Raaiat1on Hazarcs 8/15/cS All holde-s of :Ls

frcm Irradiated :nccre or CPs for nuclear

Detectors ane Cables power reactors.

research reactors

and test reactcrs.

88-62 Recent Finoings Conce~ring 8/12/8E All holders of NRC

Iroierentation of '"ality quality assurarce

Assurance Progrars ty prcgran ac;rcvai

Suo:liers of -ranspcrt for radicactsve

Paoacras material packaces.

88-61 Ccntrol Rocm viabitaotlity - All holcers of Dls

Recent Reviews of C;eratinq or CPs 'or nuclear

Exrerience power reactors.

88-60 Irndeeuate Cesign ano s/1./8 All hcIders of Ls

Installation of Watertight or C'Psfor nuclear

Peretration Seals power reactors.

88O - InaedUaOTe-ulification

Suppierent I and -ocumeniation of Fire or CPs for ruc'ear

Barrier Penetratior Seals power reactors.

88-59 MairnSteam :solatlcn Valve 8/9!E8 All holders of -Ls

Guiee Rail Failure at or CFs for nuclear

Waterford Unit 3 power reactors.

OL

• Operating License

CP

• Construction Pemrt

FIRST CLASS MAIL

UNITED STATES POSTAGE t1 FEES PAIO

USNRC

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 20555 PERMIT No. G-67 OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE, *300

IN 88-68 August 22, 1988 information notice.

No specific action or written response is required by this one of the techni- If you have any questions about this matter, please contactof the appropriate NRC

cal contacts listed below or the Regional Administrator

regional office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Mary S. Wegner, AEOD

(301) 492-7818 Charles G. Hammer, NRR

(301) 492-0919 Attachment: List of Recently Issued NRC Information Notices

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06/28/88 07/06/88 07/06/88 07/08/88

06/27/88

IN 88-XX

July xx, 1988 No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact one of the techni- cal contacts listed below or the Regional Administrator of the appropriate NRC

regional office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Mary S. Wegner, AEOD

(301) 492-7818 Charles G. Hammer, NRR

(301) 492-0919 Attachment: List of Recently Issued NRC Information Notices

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