ML17285A507

Forwards Addl Info Re Insp Rept 50-397/86-12 Concerning Equipment Qualification of Limitorque Motor Operators Toward Resolution of Remaining Open Item on Subj Audit.Grease Relief Valve Test Data & T-drain Technical Analysis Encl

ML17285A507
Person / Time
Site:	Columbia
Issue date:	06/01/1989
From:	Sorensen G WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-89-103, NUDOCS 8906070104
Download: ML17285A507 (18)

Text

A.C CELE P <TED Dl STK B t 'Tl ON DE MON iTRATIOY SYSTEM f

R EGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:8906070104 DOC.DATE: 89/06/01 NOTARIZED: NO DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION SORENSEN,G.C. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Submits addi info on Insp Rept 50-397/86-12 re equipment qualification.

DISTRIBUTION CODE: IE01D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: General (50 Dkt)-Insp Rept/Notice of Vio ation R sponse NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL

'1 PD5 PD 1 1 SAMWORTH,R 1 INTERNAL: ACRS AEOD/DEIIB 2,

1 2

1 AEOD AEOD/TPAD 1

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1 DEDRO 1 1 NRR SHANKMAN,S 1 1 NRR/DEST DIR 1 1 NRR/DLPQ/PQEB 1 1 t

NRR/DOEA DIR 11 1 1 NRR/DREP/EPB'0 1 1 NRR/DREP/RPB 10 2 2 NRR/PMAS/ILRB12 1 1 NUDOCS-ABSTRACT 1 1 OE LIEBE ,J 1 1 OGC/HDS2 1 1 REti 0,'TLE 02 1 1 RGN5 FILE 01 1 1 EXTERNAL: LPDR 1 1 NRC PDR 1 1 NSIC 1 1 D

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TOTAL NUMBER OF COPIES REQUIRED: LTTR 24 ENCL 24

WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George lVashington Way ~ Rtchland, Washtngton 99352 Docket No. 50-397 June 1, 1989 G02-89"103 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station Pl-137 Washington, DC 20555 Gentlemen:

Subject:

NUCLEAR PLANT NO. 2 ADDITIONAL INFORMATION RELATIVE TO INSPECTION 50-397/86-12, EQUIPMENT QUALIFICATION

Reference:

See Attachment 1 On March 29, 1989, Mr. A. Toth and Mr. R. Wilson of the NRC met with the Supply System to examine information regarding qualification of Limitorque motor operators toward resolution of the remaining open item, on the subject audit. As a result of that meeting, the Supply System committed to provide two additional submittals. One was for the data from our test of grease relief valves with shipping caps in place (an Executive Summary had been provided previously). The second request was for an expanded technical analysis of the test data which would allow reaching the conclusion that Supply System motor operators in containment were qualified prior to the subject audit without T-drains in place (T-drains were installed during the 1986 outage).

As promised, a copy of the grease relief valve test data is attached. A copy has been provided to the,WNP-2 Sr. Resident Inspector. The T-drain technical analysis is also attached (Attachment 2).

Very truly yours, G. C. Sor nsen, Manager Regulatory Programs (MD 280)

JER/db cc: JB Martin - NRC NS Reynolds - BCP&R RB Samworth - NRC DL Williams - BPA/399 NRC Site Inspector - 901A geof 8906070104 890601 PDR ADOCK 05000397 Q PbC

Attachment 1

Reference:

l. Letter GI2-86-0060, R.F. Heishman to G.C. Sorensen, subject "Inspection No. 50-397/86-12", dated July 30, 1986.

2. Letter G02-86-0885, G.C. Sorensen to J.B. Martin, subject "Equipment (}ualification Audit, Audit No. 50-397/86-12",

dated September 17, 1986.

3. Letter G02-87-0154, G.C. Sorensen to J.B. Martin, subject "Equipment (}ualification Audit, Audit No. 50-397/86-12",

dated April 30, 1987.

Letter, R.J. Pate to G.C. Sorensen, subject "NRC Enforcement Actions Related to Inspection No. 50-397/86-12",

dated December 16, 1987.

5. Letter G02-88-023, G.C. Sorensen to NRC, subject "NRC Inspection Report 86-12", dated January 20, 1988.

6. Letter G02-88-215, G.C. Sorensen to A.D. Johnson, subject "Additional Information Equipment qua l i fi cati on", dated October 13, 1988.

7. Letter G02-88-239, G.C. Sorensen to J.B. Martin, subject "Impaired Function Testing of Limitorque Gear box Relief Valves (Test Report EAR 88-43)", dated November 16, 1988.

8. Letter, D.F. Kirsch to G.C. Sorensen, subject "NRC Inspection at l<NP-2", dated November 25, 1988.

Attachment 2 TECHNICAL ANALYSIS OF WNP-2 IN-CONTAINMENT LIMITOR()UE MOTOR OPERATORS WITHOUT T-DRAINS INSTALLED WNP-2 has eight (8) Limitorque motor operators inside containment. Prior to the time of the equipment qualification audit in May 1986, an outage was underway and a part of the outage work was conduct of a comprehensive program to examine configuration issues of the motor operators relative to identified concern areas.

This internal Supply System program identified the need to install T-drains in these eight (8) motor operators. A Nonconformance Report was initiated and provided to the NRC E(} audit team at the entrance meeting. The T-drains were installed prior to star tup from that 1986 refueling outage to comply with Limitorque's standard configuration for RH insulated motors.

This analysis addresses environmental qualification of the motor operators without T-drains installed, for consideration relative to the period prior to installation of the T-drains.

Motor "T" Drain Desi n Feature Initial test programs ( 1968) conducted by Limitorque did not employ a motor drain design feature. The design feature was added ar ound 1972 when testing to IEEE-382-1972 was conducted (Ref. 3). To our knowledge, through discussions with Limitor que, this feature was not directly resultant from any test program anomaly or failure.

The design intent of the T-drains is to allow any condensation buildup internal to the Limitorque's motor to drain.out and preclude possible starting or running impairment due to the postulated condensate buildup. The degree of condensate buildup has never been quantified to our knowledge. The T-drain also provides a second vent path into the motor housing and thus a potentially negative effect of this design feature is present. The design provides a path to allow accident steam to be drawn in through the T-drain(s) during motor running or pressur e equalization. The other vent path is via the conduit connection between the motor and the limit switch compartment. Should the Limitorque operator be positioned in such a way that condensate/steam/spray entering the limit switch compartment could drain into the motor housing via the conduit pathway, then T-drains might provide sufficient drainage if flow rates were sufficiently low.

Mounting of the motor below the limit switch compartment is not r ecommended by Limitorque and no in-containment configuration of this type exists on WNP-2.

The principle question associated with the T-drain design feature is, "Can enough condensate accumulate in the motor, during an accident, to impair proper functioning7". Thus, conditions 'hat cause condensation (i.e., where condensation heat transfer is the dominant mode) are critical to assessing this question.

As will be, shown later, the very first Limitorque tests (without the T-drain design feature) were sufficiently harsh enough and condensation heat transfer dominated the test conditions such that the WNP-2 plant specific steam/temperature/pressure conditions were adequately enveloped. Thus the condensation conditions produced during a WNP-2 LOCA are not sufficient to require the T-drain design feature to insure the motor's safety function is achieved.

The reasoning and data presented conclude that the motor T-drains are not an essential design feature for WNP-2 accident conditions and, therefore, the qualification was not compromised during the period from November 30; 1985 unti 1 their installation in May 1986.

Motor Simi larit The Limitor que test program that demonstrates adequate performance without T-drains is described in Repor t '600198. This program tested a Reliance motor that contained a Class H insulation. This is reported by Reliance to have been a precursor to their standard Class H, Type "RH" insulation. WNP-2 in-containment Limitor que operators employ only the Class H, Type "RH" insulation. Limitorque Test Report 600376A is the qualification test report generally cited by Limitorque for qualification of these motors in BWR containments. Other than T-drains, the only configuration similarity issue of interest is the differ'ence in insulation systems. We have contacted both Reliance and Limitorque to obtain details on these Class H insulation systems and assess the differences. Clearly, if the insulation system in either the early Limitorque test (600198) or the later test (600376A) was significantly superior, the condensation buildup could possibly be tolerated to a greater degree by the superior insulation system.

Reliance reports that the older Class H system was a precursor to the "RH" system used now and that there were some differences. This information is however, proprietary ahd applicability of the 600198 qualification test report to the "RH"

-insulation system should be handled through Limitorque. Generally though, Reliance believes their "RH" insulation system design is superior to the early CLass H system used in the 600198 Limitorque test. Limitorque has stated that they will certify that the'arly 600198 test is applicable to the motor operators that employ the "RH" insulation system. Thus the testing conducted under 600198 can be used to assess the safety significance of the need for T-drains under WNP-2 accident conditions.

WNP-2 Environmental Condition 8 Limitor ue 0 erator Res onse WNP-2 is a Boiling Water Reactor (BWR). Equipment in containment is to be qualified to the WNP-2 plant specific temperature and pressur e profiles shown on Figure 1, plus margin. We generally use the BWR generic profile, as detailed jn NUREG 0588, which provides more than the IEEE-323 recommended margin of 15 F 0 above peak temperature levels. Limitorque Test 600198 tested a motor operator without T-drains to a temperature/pressure/steam profile ~reater than the WNP-2 specific profile. This is also shown on Figure 1. A 9 F margin was obtained above the WNP-2 plant specific profile. This is adequate because the WNP-2 profile contains a considerable superheat steam region and the 600198 test was performed under saturated steam conditions.

In 1981 the Supply System commissioned a test for our HHP-1 project to obtain a realistic understanding of the temperature, response of a motor operator when subjected to a superheated steam environment (Ref. 2). As shown in Figure 2, the operator's surface (housing surface) temperature rise~ rapidly to the saturation temperature of steam at the test chamber pressure (327 F, 85 psig) in 45 seconds.

Even though the chamber pressure was quickly reduced to 70 psig, the surfaces of the operator remained at the original saturation temperature. Other parts of the operator (i.e., motor stator and limit switch base) also show a somewhat slower but rapid temperature increase.

During the initial period (0-1 minute), condensation on the outside surfaces is the dominant heat transfer mode. Within this region (i.e., when the temperature of the oper ator's surface is below the satur ation temperature), condensation heat transfer is very effective and temperature of the exposed surfaces of the operator increase rapidly. A two to three minute plateau or transition period follows this where the temperature of the surface of the operator stays near the saturation temperature. Latent heat of evaporation plays a role in this leveling.

The condensate that accumulated evaporates as the radiative and convective heat transfer mechanisms attempt to raise the surface above the saturation temperature.

After the condensate has evaporated (i.e., operator surfaces are now dry), the final phase is a region where the dominant heat transfer mode is thermal radiation and convection. During this region, heat transfer is much slower.

This is because the temperature of the surface of the operator is above the saturation temper atur e of the steam. It takes approximately 30 minutes for the internal mounting base of the limit switch compartment to rise to within 10 F of the test's superheat level {Ref. 2). Test data of the motor's stator shows similar behavior. The internals of the motor lags the housing surface but leads the internal limit switch mounting base in it's climb to maximum temperature level. The motor's temperature will easily reach the maximum level within thirty minutes.

The HNP-2 plant specific profile {Figure 1, la) has a peak temperature of 320 F which is approximately 39 F above the saturation temperature (approximately 50 psia, 281 F). This condition exists for approximately 45 minutes. This is more than enough time for the phenomenon that occurred in the superheat test described above to occur. Condensation heat transfer should cause rapid heatup (within one (1) minute) of the operators surface to approximately 281 F, level off, and after a few minutes, start the slow climb toward the peak drywell temper ature. At the end of approximately five (5) minutes of accident exposure, our operators should be dry. At the end of 21 minutes, the LOCA temperature is dropping and the surfaces of the operator should be near 310 F. They then will follow (lag) the decreasing profile until a relatively long term stable period of temperature occurs which is at or below the satur ation temperature. The operators then will again be subjected to condensation exposure.

Reference 1 demonstrates operability of a motor operator, without T-drains installed, at steam temperatures exceeding the HNP-2 containment accident profile. Unlike the superheat test or the HNP-2 LOCA profile, the 600198 test was performed at sat~rated steam conditions, therefore, at higher pressures. The peak levels were 329 F and 90 psig. The operator surfaces would have experienc~d a rapid temperature increase via the condensation heat transfer mode up to 329 F within the first minute. As there was no superheat region, there would have been no drying out of this condensation. Thus any condensation that was formed in the .

motor would have remained and added to accumulation later in the test program (i.e., the post LOCA soak). These test conditions are also shown on Figure 1.

By using graphical approximation of the data from Reference 2, the surface temperature of a Limitorque operator inside the HNP-2 containment can be estimated. This is shown by Curve A in Figur e 3. Note that the level portion of operators surface temperature response curve for the HNP-2 LOCA occurs at 281 F.

Applying the same methodology to the test results of Reference 1 leads to Curve B in Figure 3. Comparison of these curves results in the conclusion that the Limitorque motor operator was exposed to hotter and wetter conditions by the 600198 test which did not have installed T-dr ains than the HNP-2 operators would experience during a LOCA. Figure 3 also shows that the operators temperature response to the 600198 test contain sufficient margin to satisfy the IEEE 323 peak temperature margin requirement.

In addition, the 600198 test greatly exceeded the HNP-2 specific profile for the remaining seven (7) days of the test. After seven (7) days gf the HNP-2 postulated LOCA, the temperature conditions have decreased to 165 F, which is near the non accident condition maximum of 150 F inside containment (see Figure 1A).

Conclusion The very first Limitor que steam tests (without the T-drain design feature) were sufficiently harsh and wet to envelop HNP-2 requirements with adequate margin.

Condensation heat transfer dominated the test conditions much more than they would in the superheated WNP-2 plant specific steam conditions. Therefore, the condensation buildup conditions produced during a HNP-2 LOCA are not sufficient to require T-drain design feature to insure the motor's safety function is achieved.

The configur ation of HNP-2 operators before May 1986 without T-drains does not invalidate their qualification. Thus, T-drains for WNP-2 motors were not a required design feature unless the mounting configuration would allow condensate to drain from the limit switch housing into the motor via the conduit connection.

As HNP-2 has no operators inside containment configured in this manner, the installations did not require T-drains.

T-drains were added to the WNP-2 in-containment motors in May of 1986 to defuse any NRC concer ns with our Limitorque operators prior to our restart following the refueling outage and have been maintained in that configuration. For the present, the Supply System intends to maintain this configuration.

References

1. WCAP-7410-L-Vl Appendix C, Franklin Institute Research Laboratories Final Report F-C2232-01, Limitorque No. 600198, "Test of a Limitorque Valve Operator Under a Simulated Reactor Containment Post Accident Steam and Chemical Environment," January 2, 1969.

2. Babcock & Wilcox Document 851-1132772-00, "Final Report for In-containment Type Limitorque Actuator Steam Line Break qualification," July 31, 1982.

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