ML20070L726

Responds to Generic Ltr 89-10,Suppl 3, Consideration of Results of NRC-Sponsored Tests of Motor-Operated Valves

ML20070L726
Person / Time
Site:	Peach Bottom, Limerick
Issue date:	03/13/1991
From:	Beck G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-89-10, NUDOCS 9103200195
Download: ML20070L726 (9)

Text

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l 10 CFR 50.54(f)

GL 89-10 PHILADELPillA ELECTRIC COMPANY NUCLEAR GROUP HEADQUARTERS 955-65 CHESTERBROOK BLVD.

WAYNE, PA 19067 5691 (2 5 5) **8*

March 13, 1991 Docket Nos.

50-277 50-278 50-352 50-353 License Nos.

DPR-44 DPR-56 NPF-39 NPF-85 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

Peach Bottom Atomic Power Station, Unita 2 and 3 Limerick Generating Station, Unita 1 and 2 Response to Generic Letter 89-10, Supplement 3,

" CONSIDERATION OF THE RESULTS OF NRC-SPONSORED TESTS OF MOTOR-OPERATED VALVES"

REFERENCE:

December 14, 1990 letter from PECo to NRC, 30-Day Response to Generic Letter 89-10, Supplement 3

Dear Sir:

In parallel with the NRC staff's activities leading to Generic Letter (GL) 89-10

" Safety-Related Motor-Operated Valve Testing and Surveillance," the staff performed tests of motor-operated valves (MOVs) as part of an ongoing research effort.

The NRC-sponsored tests were focused on valves typically used for containment isolation in the supply line to the High Pressure Coolant Injection (HPCI), Reactor Core Isolation Cooling (RCIC), or Reactor Water Clean-up (RWCU) systems at Boiling Water Reactor (BWR) plants.

Because the test results indicated that sufficient thrust for opening and closing MOVs may not be predicted using standard industry calculations with typical friction factors, the NRC issued Supplement 3 to GL 89-10 (dated October 25, 1990).

Philadelphia Electric Company N

OS$ received GL 89-10, W

Supplement 3 on November 14, 1990.

09 BWR licensees were requested to notify the NRC within 30 Nc' days of receipt of GL 89-10, Supplement 3 that a plant-specific safety a

assessment report addressing, as a minimum, the factors described in ou GL 89-10, Supplement 3 was available on site for review.

BWR 88 licensees were also requested to notify the NRC within 30 days of receipt of GL 89-10, Supplement 3, of any MOVs that they believe to have deficiencies of greater safety significance than those used for m

3$

containment isolation in the supply to the HPCI, RCIC or RWCU Systems 300-or in the line to the isolation condenser.

The referenced letter provided Philadelphia Electric Company's 30-day response to GL 89-10, Supplement 3 for Peach Bottom Atomic Power Station (PBAPS), Units 2 IIgg

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, Response to GL 89-10, Supplement 3 March 13, 1991

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Page 2 and 3, and Limerick Generating Station (LGS), Units 1 and 2.

BWR licensees were requested to provide within 120 days of receipt of GL 89-10, Supplement 3, the criteria that were applied in determining whether deficiencies exist in the HPCI, RCIC, and RWCU MOVs, and in MOVs in the isolation condenser lines and in any other MOVs considered to be more safety significant.

BWR licensees were also requested to identify any deficient MOVs and provide a schedule for necessary corrective actions.

Accordingly, thiu letter provides the 120-day response to GL 89-10, Supplement 3 for PBAPS, Units 2 and 3, and LGS, Units 1 and 2, The attachment to this letter provides the criteria applied in our review of potential PBAPS Units 2 and 3 MOV deficiencies and identifies one MOV that may be deficient, the PBAPS Unit 3 RWCU Outboard Isolation Valve (MO 12-18 ).

To correct this MOV deficiency, the torque switch setting will be adjusted during the next refueling outage to achieve a greater thrust.

At LGS, Units 1 and 2 the isolation valves in the HPCI, RCIC, and RWCU systems are globe valves.

Globe valves are not subject to the same disk friction concerns as gate valves.

Therefore, none of these LGS MOVs are considered to be deficient.

Upon review of the configuration and operating conditions for other plant systems at PBAPS and LGS, we have concluded that there are no other MOVs with potential deficiencies that have a greater safety significance than those in the HPCI, RCIC and RWCU systems.

There is no isolation condenser at PBAPS or LGS.

As stated in our 30-day response, certain compensatory actions were implemented at PBAPS to address the differences between the PBAPS design and the assumptions about small leak detection capability in the generic safety assessment performed by the BWR Owners' Group.

Since only one MOV is currently considered deficient, some of those actions are no longer necessary and have been ceased.

The PBAPS plant-specific safety assessment has been revised to address these revised compensatory actions and is available on-site for review.

If you have any questions or require additional information, please do not hesitate to contact us.

Very truly yours,

,s:r..-

G.

J.

eck, Manager Licensing Section Nuclear Engineering and Services Attachment cc:

T. T. Martin, Administrator, Region I, USNRC J.

J. Lyash, USNRC Senior Resident Inspector, PBAPS T.

J. Kenny, USNRC Senior Resident Inspector, LGS l

CDMMONWEALTH OF PENNSYLVANIA:

Ss.

COUNTY OF CHESTER D. R.

Helvig, being first duly sworn, deposes and says:

That he is Vice President of Philadelphia Electric Company; that he has read the 120-day response to Generic Letter 89-10, Supplement 3, and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of hic knowledge, information and belief.

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Vice Presid.n Subscribed and sworn to beforemethis/

day of March 1991.

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]F LL M (Y Ec (l

Notary Public NOTANAL SEAL PATPICIA A.JOflES, Nowy Public Cey of Pniaderno. PNia. CcuM/

P,tv Corm s;m Etyres Cec. 13 1994

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ATTACHMENT Peach Bottom Atomic Power Station, Units 2 and-3 i

120

-Day Response to-1 Generic Letter 89-10 Supplement 3 i

Page 1 of 6

1.0 INTRODUCTION

Generic Letter 89-10, Supplement 3, " Consideration Of The Results of NRC-Sponsored Tests Of Motor-Operated 1 Valves," requested Boiling Water Reactor (BWR) licensees to determine-the "as-is" capability of and identify deficiencies in selected containment isolation motor operated valves-(MOVs). These include-MOVs in the steam lines of the high pressure coolant injection (HPCI) and the 4

reactor

're isolation' cooling (RCIC) systems and_in the reactor water clean-up (RWCU) supply. In addition it requested licensees to identify any other valves which could be of-greater safety-significance. The basis for this request was the results of-NRC-sponsored MOV testing, conducted by Idaho National Engineering.

Laboratories (INEL).

L The INEL testing involved operation of the MOVs under severe-fluid conditions. The test results appear to-indicate that thrusts greater than those. predicted from standard industry calculations are required to operate the valves.-This evaluation provides a determination of the capability of the containment-isolation MOVs in the HPCI and RCIC steam lines and the RWCU-suction line at Peach Bottom Atomic Power Station (PBAPS), Units:

2 av

,a valves to be evaluated aro:

ho-2(3)-23-15,16 HPCI Steam Supply Inboard'and Outboard Containment Isolation Valves MO-2(3)-13-15,16 RCIC Steam SupplyLInboard-and Outboard Containment Isolation Valvec MO-2-12-15,18 Unit 2 RWCU Supply' Inboard-and Outboard Containment 1 Isolation Valves-MO-3-12-18 Unit 3.RWCU Supply Outboard containment Isolation Valve 1

9 ATTACHMENT Peach Bottom Atomic Power Station, Units 2 and 3 l

120 - Day Response to Generic Letter 89-10 Supplement 3 Page 2 of 6 MO-3-12-15 (Unit 3-RWCU Inboard Containment Isolation) is a globe l

valve-and is not included in the scope of this analysis. This is due to the fact that globe valves are not subject to the.same disk friction concerns as gate valves, and therefore were not tested by INEL.

4 Review of the function of other motor operated gate valves indicates that there.are no other valves with greater safety 4

significance than those indicated. This-is based on review;of-the-4 appropriate system Piping & Instrumentation Diagrams-(P& ids) and applicable sections of the Peach Pottom Atomic Power station Updated Final Safety Analysis Report (UFSAR).

Both Generic Letter 89-10 and its Supplement 3 present the use of a "two-stage " approach to evaluate MOVs for which in situ design-i basis testing is not practicable. Following this approach, the MOV requirements are determined using the best data available'and 1

analytical methods. When test. data applicable to the design basis l

conditions becomes available, it will be used to demonstrate MOV.

operability. This approach will be utill:ed to evaluate _the-subject HPCI, RCIC, and RWCU isolation valves. By using the two-stage approach, results.and recommendations contained in this j

analysis may be revised as more applicable, definitive test data becomes available.

Design calculations were first reviewed to determine available i

margins included. Baseline diagnostic test results were then j

compared to target thrusts developed fr'm calculations. The test i

results were also compared to applicable results from INEL.-

i Review of design calculations for the Walworth valves used in the HPCI and RCIC and Unit 2 RWCU applications indicate that separate i

. factors are assigned for differential pressure (dP) load and seating force.

As a result,-the total valve. factor:is greater than the standard value of 0.3. This provides a degree of margin.

in the calculated thrust value.

i All design calculations' include margin-in that the design basis-pressure corresponds to initial Safety Reliet Valve actuation.

This is approximately 100 psi above'the normal reactor operating i

pressure.

In addition to the margin in the,Walworth design-I calculations, the target thrusts for diagnostic testing _of all the subject __ valves include a 30% margin.above calculated thrust.

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l ATTACHMENT Peach Bottom Atomic Power Station, Units 2 and'3

}

120 - Day Response to-t Generic Letter 89-10 l

supplement 3 l

-Page 3 of 6 This margin conservatively accounts for_ uncertainties in applying static test results to thrust at dP.

l The performance acceptance criteria applied to valves with a similar gate design but different size (le; MO-2(3)-23-15,16),

- than those tested by INEL, was valve factor; capability.

For valves with a different gate design and size (iet MO-2(3) 15,16) the performance criteria used was a comparison of_the thrust at TS Trip to that of the target thrust.

For valves with i

similar gate design and size (.ie; MO-2-12-15,18 and MO-3-12-18) the performance criteria applied was a comparison of thrust required to -close the INEL velve with the thrust at TG Trip of.

1 the PECo Valve.

i 2.0 MOV EVALUATION I. MO-2(3)-23-15,16 HPCI Steam Supply Inboard and Outboard Containment Isolation Valves These valves are Walworth 8-inch flexible wedge gate valves. The calculated design basis dP is 1116 psid.

MO-2(3)-23-15_are equ pped with Limitorque SMB-0 motor operators. MO-2(3)-23-16 are i

equipped with Limitorque.SMB-1 motor operators.

Diagnostic testing provided the following results.

Valve No.

Target Thrust Thrust (1bs.)-

Valve i

(lbs.)

at Torque Switch Factor (TS)iTrip Capability.

?

f MO-2-23-15 24',125 28,227 0.59 MO-3-23-lb

-20,966 20,100 0.39 MO-2-23-16 24,125 29,158 0.61 MO-3-23-16 24,125 26,000 0.53 l

A similar Walworth valve in 6-inch size was tested by.INEL and exhibited valve factors in the range of 0.30-to 0.34 when tested-

-at 1100 psid. Due-to the difference in sizes.between-the INEL valve and the HPCI valves (6-inch vs. 8-inch), direct comparison of thrust requirements is not appropriate. A more appropriate comparison is between valve factors since they are not dependent on valve size.

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t ATTACHMENT Peach Bottom Atomic Power Station, Units'2 and 3 120 - Day Response to Generic Letter 89-10 Supplement 3 Page 4 of 6 Thrust measurements of MO-2-23-15, MO-2-23-16, and MO-3-23-16 indicate that they are all capable of meeting or exceeding the target thrust. In addition they are capable of overcoming a valve factor in excess of that derived from INEL data. These-valves are judged capable of performing their design function.

While the thrust developed by'MO-3-23-15 is slightly below the target thrust, it is not possible to increase the thrust beyond this level since the valve is currently at its maximum torqua nwitch setting. We judge however that this valve is capable of performing its design function since it is capable of overcoming a valve factor in excess of that derived from the INEL data.

II. MO-2(3)-13-15,16 RCIC Steam Supply Inboard and Outboard containment Isolation Valves These valves are Walworth 3-inch solid wedge-gate valves. Due to their smaller size and different-disk type,:we judged-that the results of the INEL testing are not'irectly applicable to-these d

valves. Because of this, a comparison of thrust.at TS Trip to the target thrust was used to determine valve performance.

Diagnostic testing provided the following results.-

Valve No.

Target Thrust (lbs.)

Thrust at TS Trip (lbs.)

MO-2-13-15 5060

'5300 MO-2-13-16 5060 5140 MO-3-13-15 5060 6100 MO-3-13-16 5060

-4480' A review of the test results-indicate that all valves are capable of meeting the target thrusts with the exception of valve MO 13-16.

While the thrust at torque switch trip for valve MO-3 16 is below the target thrust, it_provides a margin of approximately 15% above the calculated design thrust.

We have concluded this margin provides reasonable assurance that'the valve is capablelof performing its intended-safety function.

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ATTACHMENT.

Peach Bottom ntomic Power Station, Units 2=and 3

-120 - Day Response to; Generic-Letter 89 Supplement 3 4

Page 5 of 6 This conclusion is based on the conservative margin provided in l

the target thrust versus design thrust values in addition to inaccuracies in diagnostic-test equipment.

While we have concluded that MO-3-13-16 is capable of performing-its intended safety function, the torque switch setting will be adjusted to achieve the target thrust during the next Unit 3 refueling-outage.

This adjustment will provide additional assurance of satisfactory valve performance.

III. MO-2-12-15,18 Unit 2 RWCU-Supply Inboard and Outboard Containment Isolation-

. Valves These valves are Walworth 6-inch flexible wedge gate valves. The calculated design basis dPs are-1142 and 1173 psid for MO-2-12-15 and MO-2-12-18, respectively. _-The valves are-equipped with' Limitorque SMB-00 motor operators.

Diagnostic testing provided the followingsresults.

Valve No.

Target Thrust-(lbs.)

Thrust at TS Trip-(lbs.)

MO-2-12-15 16,695

-15,194 MO-2-12-18 16,695 20,200 INEL test results from a similar 6-inch Walworth model valve indicate that a thrust of 11,500 pounds was= required to close this valve under-a dP of 1100' psi. Due to the similarity-in design basis.dPs and valve' design,-the thrust at TS Trip for the Unit 2 RWCU valves was compared to theLthrust required to close' 4

the INEL valve. This comparison was used.to determine valve-performance.

The diagnostic test results-indicate that both valves-are capable of meeting the thrust required based on-the'INEL data.LIn addition'the INEL test results indicate that-the target thrust values are conservativ3.-These valves are. judged capable of-performing their design function.

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-ATTACHMENT-Peach Bottom Atomic Power Station, U-4ts 2 and 3-120 - Day Lasponse to Generic Letter 89-10 Supplement 3 Page 6 of 6 IV. MO-3-12-18 Unit 3 RWCU Supply Outboard-Containment Isolation Valve This valve is a 6-inch Anchor Darling flexible wedge gato valve equipped with a Limitorquo SMB-0 motor operator.

The calculated design basis dP is 1173 paid and a valve factor of 0.3 was used in the thrust calculations.

Diagnostic test results indicate that this valve can deliver a thrust of 18,000 pounds at its current torque switch setting.

A 6-inch Anchor Darling flexible wedge gate valve was tested by INEL and required a thrust of 19,500 pounds to close at a dP of approximately 900 psi.

Results of valve inspection indicate-that;the valve tested'by INEL during Phase 2. testing may not be representative of industry supplied valves. It was noted that the disk edge is sharper and the hard-facing thinner than that on velves normally provided by Anchor Darling. While the inspection results indicate that the test data may not be applicable to11ndustry-valves, the tests may indicate that higher closing thrusts could be required. The thrust currently developed by MO-3-12-18 does not appear sufficient at the present torque switch setting. 7t has been concluded that the torque switch setting will be adjusted to provide assurance that the valve will develop a thrust of 20,000 pounds under design basis. conditions. To attain this, a target thrust of 24,000 pounds should be used during static baseline.

testing.

1 3.0 CORRECTIVE ACTIONS

1) The torque switch setting of the'PBAPS Unit 3 RWCU Supply Outboard Containment Isolation Valve (MO-3-12-18)'will be adjusted to achieve a target thrust of 24,000 lbs during the next T.'.it 3 refueling outage.

2) The torque switch setting of the PBAPS Unit 3-RCIC Steam-Supply outboard Containment Isolation Valve (MO-3-13-16) will be adjusted to achieve the target thrust of 5060 lbs. during the next Unit 3 refueling outage.

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