ML17213B077

Requests,Within 15 Days,Assessment of Operability of Henry Pratt R1A Butterfly Valves Used for Purging & Venting of Containment & Commitment That Subj Valves Will Be Sealed Closed Per SRP Section 6.2.4,II.6.f

ML17213B077
Person / Time
Site:	Saint Lucie
Issue date:	02/16/1983
From:	Clark R Office of Nuclear Reactor Regulation
To:	Robert E. Uhrig FLORIDA POWER & LIGHT CO.
References
NUDOCS 8303020211
Download: ML17213B077 (10)

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V FEB 16 1983 4~ 830 DC+ gs -Qi&,

Docket No. 50-335 Dr. Robert E. Uhrig Vice President Advanced Systems

& Technology Florida Power

& Light Company P. 0. Box 529100 Miami, Florida 33152

SUBJECT:

COMPLETION OF VALVE OPERABILITY REVIEWS FOR LARGE PRATT BUTTERFLY VALVES USED FOR PURGE OR VENT OF CONTAINt1ENTS,- ST.

LUCIE UNIT 1.

In our letter of November 28, 1978 we identified the. generic concerns of purging and venting -of containment to all operating reactor licensees and requested your response to these concerns.

Our review of your response was interrupted by the TNI accident and its demands on staff resources.

Consequently, an Interim Position on containment purging and venting was transmitted to you by letter dated October 23, 1979.

You were requested to implement short-term corrective actions to remain in effect pending completion of our longer term review of your response to our November 28, 1978 letter.

One of the remaining interim corrective actions (and the subject of this letter) still in place while our longer term review is being completed is to:

"Maintain the containment purge and vent isolation valves closed whenever the reactor is not in the cold shutdown or refueling mode until such time as you can show that:

a.

All isolation valves greater than 3" nominal diameter used for containment purge and venting operations are operable under the most severe design basis accident flow condition loading and can close within the time limit stated in your Technical Specifications, design criteria or operating procedures.

The operability of butterfly valves

may, on an interim basis, be demoIIstrated bg limiting the valve to be no more than 30o to 50 open (90 being full open).

The maximum opening shall be determined in consultation with the valve supplier.

The valve opening must be such that.the critical valve parts will not be damaged by DBA-LOCA loads and that the valve will tend to close when the fluid dynamic forces are introduced."

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FEB 1 6".0 tOr. Robert E. Uhrig However, recent information concerning the operability of large-diameter Pratt butterfly valves (of the generic family R1A or NR1A) in the event of a

DBA-LOCA has raised concern whether your Justification for operability provides the required assurance that these valves will close.

Enclosure 1 provides the background information and the bases for our concern.

Therefore, pursuant to 10 CFR 50.54(f), you are requested to inform ua in writing within 15 days of receipt of this letter:

l.

Your assessment of the operability of your large-diameter Pratt purge and vent valves in light of the concerns outlined in Enclosure 1, and 2.

Whether or not you intend to maintain the purge and vent valves sealed closed in accordance with Standard Review Plan Section 6.2.4, II.6.f and to verify them to be closed every 31 days whenever the reactor is not in the cold shutdown or refueling mode until such time as you submit acceptable information that demonstrates that your large-diameter Pratt purge/vent valves will operate in the event of a DBA-LOCA.

This information will enable the Commission to determine whether or not further action should be taken to modify, suspend, or revoke your license.

The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OHB clearance is not required under P.L.96-511.

Sincer ely,

Enclosure:

As stated cc w/encloaur e:

See next page cc:

See revious concurrence a

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Dr. Robert E. Uhrig 2

However, recent information concerning the operability of large-diameter Pratt butterfly valves (of the generic family R1A or NR1A) in the event of a

DBA-LOCA has raised concern whether your interim position jrovides the required assurance that these valves will close.

Enclosure 1 provides the background information and the bases for our concern.

Therefore, pursuant to 10 CFR 50.54(f), you are requested to inform us in writing within 15 days of receipt of this letter of. your commitment that your large-diameter Pr att R1A (or NR1A) purge/vent valves will be sealed closed in accordance with Standard Review Plan Section 6.2.4, 11.6.f.

Furthermore, pending receipt from,you of acceptable information that demoijstrates that your large-diameter Pratt purge/vent valves will operate in conformance with the above-quoted interim corrective action, these valves Hill be verified to be closed at least once every 31 days.

4 The reporting and/or recordkeeping requirements contained in.this letter affect fewer than ten respondents; ther'efore, ONB clearance is not required under P.L.96-511.

Sincerely, Encl osur e:

As stated cc w/enclosure:

See next page Robert A. Clark, Chief Operating Reactors Branch ¹3 Division of Licensing DISTRIBUTION Docket File Local'PDR ORB ¹3 Rdg D.Eisenhut JHeltemes RAClark PKreutzer (3)

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Florida Power

& Light Company CC:

Harold F. Reis, Esquire Lowenstein,

Newman, Reis

& Alexrad 1025 Connecticut

Avenue, N.W.

Washington, D. C.

20036 Norman A. Coll, Esquire McCarthy, Steel, Hector

& Davis 14th Floor, First National Bank Building Miami Florida 33131 Mr. Jack Schreve Office of the Public Counsel Room 4, Holland Building Tallahassee, Florida 32304 Resident Inspector c/o U.S.N.R.C.

7900 S.

A1A Jensen Beach, Florida 33457 Administrator Department of Environmental Regulation

.Power Plant Siting Section. "

State of Florida 2600 Blair Stone Road

'allahassee, Florida 32301 Mr. Weldon B. Lewis County Administra tor St. Lucie County 2300 Virginia Avenue, Room 104 Fort Pierce, Florida 33450 U.S. Environmental Protection Agency Region IV Office ATTN:

Regional Radiation Representative 345 Courtland Street, N.E.

Atlanta, Georgia 30308 Mr. Charles B. Brinkman Manager - Washington Nuclear Operations C-E Power Systems Combustion Engineering, Inc.

4853 Cordell Avenue, Suite A-1

Bethesda, Maryland 20014 Regional Administrator Nuclear Regulatory Commission, Region II Office of Executive Director for Operations 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 State Planning and Devel pment Clearinghouse Office of Planning and Budgeting Executive Office of the Governor The Capitol Building Tallahassee, Florida-32301

ENCLOSURE EVALUATION OF HENRY PRATT R1A BUTTERFLY VALVES USED FOR PURGING AND VENTING IN OPERATING PLANTS Back round On August 3, 1982, the evaluation was completed for the 48 inch Pratt butterfly purge valves at Three Hile Island 1 (THI-1)..The qualifica-tion on these valves was found to be insufficient to demonstrate th ability of these valves to close in the event of a LOCA accident.

The major reason for this finding was the determination that the shaft stress would exceed allowable stress when experiencing worst case LOCA torque loads.

A number of operating plants have Pratt butterfly valves of the sme generic family (RlA or NRlA) and approximate size as the 48 inch RlA butterfly valves at Three Hile Island 1.

Some of'these plants have agreed to maintain these valves sealed closed in operating ides above col'd shutdown.

A larger number of plants,

however, do operate these valves for some period<*of time during operating

modes, opening the valve to a'imited maximum 'opening.

The limitation on maximum value opening has been determined by the licensees in consultation with the valve vendors in accordance with the Staff Interim Position of October 23, 1979.

The basis for this position was that for most. butterfly valves the highest torque lo'ads under flow would occur at the higher angles of opening.

Sub-

'equent testing has revealed that for some valve installations downstream of an elbow the higher torques may be experienced at smaller angles of opening but for the large majority of valve installations the higher torque at higher angles is valid.

For most of the butterfly valves used for purging and venting operations a maximum opening limitation of 50 degrees has produced sufficient con-fidence in the valve's ability to close in the event of a l.OCA to allow continued use of these valves while qualification was progressing.

In June 1981, ho~ever, Henry Pratt Valves began to inform utilities operatin'g with 48 inch and larger RlA and NRlA model valves that addi-tional restrictions might be required for these valves in order to assure the ability of these valves to close under LOCA loads.

Aqcord-ing to Pratt analyses, the valve restrictions mu1d be a maximum opening of 30 degrees to 55 degrees, depending on the individual valve or operator.

Since that time, a number of qualification reports for these valves have been submitted for NRC staff review.

The aajonty 'of these reports have been performed f'r valves closing from the full open (90 degrees) position.

These analyses have shown the valves to be overstressed for this angle of opening.

Pratt has recommended smaller maximum angles of opening for',.

these valves but no analysis has been done to show ttg acceptability of operating the valves at the lower ang'les of opening.

Two of the licensees have submitted reports calculating valve and operator stresses at the lower-angles of opening.

These reports were the Turkey Point 3 and 4 report submitted September 17, 1982 by Florida Power and Light (FPEL) and the

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ed Three Nile Island (THI-1) report submitted by General Public Utilities

{GPU).

As previously stated, the THE-1 report was evaluated on August 3, 1982 and found insufficient to qualify'he valves to close aaainst LOCA loads.

v The Turkey Point 3 and 4 report was for 48 inch and 54 inch Pratt RlA butterfly valves.

These valves were to be blocked to 35 degrees and 30 degrees respectively.

The peak containment pressure was not used in qualifying these valves but rather a percentage of that pressure by taking credit for the fact that these valves would begin to close before

'he containment would reach its peak pressure.

Enveloping static seismic loads of gx = 3, gy = 3 and gz = 4 were used in analyzing the 48 inch valve but actual required seismic loads of gx = 1.5, gy = 1.5 and gz = 1.15 were used in analyzing the 54 inch va'lve.

The calculated shaft stresses for the Turkey Point 48 inch and 54 inch valves were 27,861 psi and 26,534 psi respectively.

The analysis used a shaft stress allowable"of 30,000 psi.

'This value was based on the

'ASHE.allowable of 1.5 Sm for pressure retaining code parts.

Effectively, 30,000 psi would be a plriimum yield strength.

At this point a small amount of permanent deformation would be experienced.

The calculated values are 93 per cent and 88 percent of this yield point.leaving small margins.

In addition, the values calculated were determined on the basis of straight l.ine aooroach flow.

Yhe actual installqt<on.

n these valves have e'Ibows and bends upstream which wou'id d>start tive flow profile to these valves and change the torques experienced by these valves.

Tests performed on other model valves have shown'the effect of upstream elbows as increasing the torque by as much as 100 percent.

As no information has been submitted to date on the effects of upstream elbows on this model valve, it is uncertain what the nagni>>

tude of the increase on torque would be on this valve.

The small margins remaining for the shaft stress for these valves is inadequate to cover the concern of upstream elbows.

Consequently, the qualifica-tion submitted for the Turkey Point 3 and 4 valves is insufficient to demonstrate the ability of these valves to close against LOCA loads.

Although there are some design differences in the RlA series of butter fly valves installed in purge and vent systems of operating nuclear

plants, the inadequacy of the analysis submitted to qualify these valves to'close, in conjunction with the fact that the analyses submitted for the THI-1 and Turkey Point 3 and 4 were for the lowest angles of open-ing, indicates that the Interim Position of October 23, 1979 is insuf-.

ficient to provide adequate assurance that the RlA series Pratt butter-:;.

fly valves used for purging and venting in nuclear pla'nts will close in the event of a LOCA.

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