ML20077D944

Forwards Analysis of Grease Samples Taken from Five MOV Gear Cases at Facilities as Justification of Deferral of Sampling of Sixth Safety Injection Accumulator Isolation Valve.Gear Cases of Limitorque Operators Environmentally Qualified

ML20077D944
Person / Time
Site:	Byron
Issue date:	05/29/1991
From:	Schuster T COMMONWEALTH EDISON CO.
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
NUDOCS 9106050289
Download: ML20077D944 (9)

Text

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._ _ Ctmmsnwealth Edis n L O 1400 Opus Place

. .- O h Downsrs Grova, Illinois 60515 N

t May 29, 1991

-t Dr.' Thomas E. Murley, Director Office of Nuclear Reactor Regulation ,

U.S. Nuclear Regulatory Commission Washington, DC 20555 Attn: Document Control Desk

Subject:

Byron Station Units'I and 2 .  ;

Environmental Qualification of Grea% Mixtures in the Main Gear Case of- Limitorque . Operators NRC_Duket_Nm_EQ-35_4_anLE-455 '

Reference:

(a) November 21, 1990 letter from A. Checca to Dr. T.E.

Murley conveying a Commonwealth Edison Company (CECO)

-posttion on the environmental _ qualification:of. grease mixtures present in MOV gear cases at Byron Station..  !

Dear Dr. Murley:

h The purpose of this-letter is to convey the analysis of grease samples taken from five Motor Operated Valve (MOV) gear cases-at Byron Station.- In addition, this letter contains justification for deferral of.the sampling of'a sixth valve, the ISI8808C Safety-Injection ~ Accumulator? Isolation Valve, to avoid unnecessary radiation exposure for-station personnel; This letter _

satisfies a commitment to provide 1analysisLresults'for MOV gear cases'which-contain grease mixtures in excess'of 5%. The grease samples n re taken

, approximately six months after' CECO'sLprevious letter of Reference (O in- l p accordance-with the written commitment of that letter. "

~ Enclosed is a-letter from the CECO Nuclear Engineering Department to the; Byron Station Manager providing a Supplemental Justification for Continued l

Operation for the six Byron Unit 1 Valves which contain grease mixtures in

.their motor operator gear cases in excess of 5%.' Attachments B'and C of the enclosed---letter:contain the sample-and sample analysis resultsJfor-five'of the:

six valves;-

L . Attachment A of=the enclosed letter provides the engineering- _

i justification for deferral.of the sampling of 1SI8808C._unt11 the September:

1991 Unit 1 Refueling.0utageL1The valve is-located in a-radiation' field-in-which the two workers obtaining the' grease sample:would acquire an estimated-

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aggregate dose of'250 mrem.. Deferral-of the sampling of 1518808C will ,

therefore avoid this unnecessary exposure. '

Evaluation of-the sample' analysis-results;and:extrapolationiof.those.

E .results-to the sixth valve has led'.to the conclusion that the grease within l- all six valves w1111 continue..to perform its intended lubrication function

funtil the September 11991 Refueling ~0utageLfor Byron Unit:1. _.

9106050289~910529 ' [

LPDRu .ADOCK 05000454  ;

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'Dr. Thomas E. Murley May 29, 1991 4

As a point of clarification, regarding Attachment C - page 6, the units of measure applicable to the radiation exposure under normal conditions is

" Rads". The values of exposure given in this table represent the Total l

Integrated Dose, i.e. the total radiation dose the equipment will be exposed to under normal operating conditions over the 40 year life of the plant.

Please direct any questions you may have concerning these matters to this office.

Respectfully, L &* d/ /

( Terence K. Schuster Nuclear Licensing Administrator Enclosure cc: A.H. Hsia - Project Manager, NRR H. Kropp - Senior Resident Inspector, Byron A. Bert Davis - Regional Administrator - RIII 25 rn is b

e rg/650:9&10

l .

Enclosure May 15, 1991 In reply refer to CHRON $

167379 TO: R. Pleniewicz

SUBJECT:

SUPPLEMENT TO THE JUSTIFICATION FOR C0KIINUED OPERATION (JCO)

RECARDING BYRON UNIT 1 VALVES CONTAINING KIXED CREASE 4

Reference:

(a) November 5,1990 S. Hunsader/E Swartz Letter to R.

Pleniewicz (Chron #158637)

Attached is an updated evaluation applicable to the JCOs for Byron Unit 1 valves ICV 112B, ICV 112E, ICS009A, 1SI8809B, 1SI8801B, and 1SI8808C. These JCOs have been re-evaluated based on new grease samples taken on April 26, 1991 and May 3, 1991. The valve operators had been found in November, 1990 to contain small quantities of lithium based grease believed to be Sun 50 EP in the intended calcium based grease used in the main gear case (ie, Exxon Nebula EP1). The amount of Sun 50 EP grease ranged from less than 5 percent to 27 percent. Reference (a) provided the JC0 that addressed this condition.

In reference (a) the Nuclear Engineering Department (NED) had determined that the presence of Sun 50 EP in the percentages found would not impair the lubrication capability of the Exxon Nebula EP1 nor impact the capability of these valves to perform their intended safety related functions. This determination was based on the fact that there was no apparent degradation of the grease due to the mixture and that the present lubricant vevid be removed no later than the next refueling outage, scheduled to occur in Ceptember, 1991. In November, 1990, as an additional precaution,-NED reccmaended that the valve grease be sampled every six months to confirm that no change in grease properties is occurring. This resampling was recently completed.

On April 26,1991, 5 of the 6 valves were re-sampled for the purpose of evaluating the condition of the grease. The five valves sampled were ICV 112B, ICV 112E,1CS009A, ISI8809B and ISI8801B. The sixth valve, 1SI8808C was not sampled due to ALARA considerations. However, not sampling this valve is acceptable. The basis for this is presented in Attachment A.

The results of the recampling are presented in Attachment B. The quantity of Sun 50 EP mixed with the Exxon Nebula EP1 in the samples taken on April 26, 1991, showed some percentage difference to the samples taken in November, 1990. Though the mixture of the Sun 50 EP and the Exxon Nebula EP1 greases is essentially uniform, the mixture is not completely homogeneous. Therefore, the differences seen are considered to be normal and are considered to be attributed to two different samples being taken at two different times.

SCH/ajs ZDESIGN/496-1

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Attachment C provides the evaluation of the results of the resampling, hp

! results for valve ICV 112E were unexpected, since similar valves in sinjiar j environments showed no appreciable change. -As a result, 3 valves (ICV)12B, ICV 112E and 1S18801B) were resampled on May 3, 1991. The new sample result j for valve ICV 112E is considereo to be representative of the valve grease

)- condition.

As shown in the attachments, the percentages of Sun 50 EP are not causing deterioration of the grease and, therefore, NED concludes that the grease will continue to perform'its intended lubrication function until the next refueling j outage scheduled for September, 1991.

I The attached infor1 nation provides more detail on the conclusions in this I letter. If further information is required, please contact Steve Hunsader,

! X7235, or Doug Swartz, X7369.

3 I

Shk9/

S. Hunsader

} Corporate EQ Coordinator l ,

1 C .r - y ,

i E.-D. Swar6 #

PWR Systems Design Supervisor ,

l l attachment l cc: F. Lentine-j N. Smith

( K. Kofron T. Kovach D. Kruger i D.-Czerniakowski 5

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SCH/aja

- -ZDESIGN/496-2 i

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Attachment A Byron Station i Unit 1 JUSTIFICATION TO OMIT VALVE ISI8808C FROM OPERATOR GREASE RESAMPLING On April 26, 1991, and May 3, 1991, five of the six valves were resampled for the purpose of evaluating the condition of the grease. Valve-ISI8808C was not resampled at this time because of ALARA considerations. For the five other valves, redundant equipment is available to satisfy the safety function.

Redundant equipment does not exist for the valve, 1SI88080. However, ISI8808C is normally open, maintained de-energized, and is not required to change position to mitigate the consequences of an accident. Thus any lubrication deficiencies would not impair the safety function of this valve. Later in the accident, closure of the valve may be required to prevent unnecessary nitrogen introduction into the RCS. However, alternate methods of satisfying this non-essential function are described in the Emergency Operating Procedures, and failure of this valve to close is fully bounded by the existing accident analysis.

The normal environmental parameters and percent concentrations of Sun 50 EP grease of the five otner valves are representative of the environmental conditions and the lubricant installed in the ISI8808C valve. Accordingly, the samples taken for the five other valves represents any trend that may be applicable to the ISI88080.- Since the grease in the five other valves-is basically unchanged, there_is reasonable assurance that the grease in valve ISI8808C is also unchanged and is in an acceptable condition. Therefore, no sampling of the ISI8808C valve is considered necessary until the- September, 1991 refueling outage.

L 9CH/aja ZDESIGN/496-3

. 1 Attachment B Byron Station - Unit 1 4 RES6LTS OF THE LIMITORQUE GREASE SAMPLING AND TESTING FOR FIVE UNIT 1 MOTOR l OPERATED VALVE (MOV) ACTUATORS.

A) Ouantity of Sun 50 EP Mixed with Exxon Nebula EP1 1

November, 90 April, 91

! Valve Ig2 Mid Eq.t 19.2 His D9.t 1CS009A 8 NA (5- 17 NA <5 ICV 112B 25 27 24 20 20 20 l

ICV 112E 13 13 13 8 10 10

)'

1SI8801B 7 7 7 <5 5 5 3

ISI8808C (5 7 7 * *

• 1SI8809B 10 10 10 7 6 6 f

• No sample taken.

1 B) The results of the April and May, 1991 sensory inspection of the grease samples indicates that the camples were of equivelent consistency of new grease and there was no burnt odor.

4 C) ASTM D-1403 Penetration (vorked)

Valve November. 1990 April 26. 1991 May 3. 1991 3

ICS009A 328 339

• ICV 112B 294 279 298 1CV112E 305 253 310 ISI8801B 305 332 334 1SI8808C 287 * *

< ISI8809B -317 313 *

• No sample caken. ,

l ** On May 3, 1991 a resampling of.three valves was performed to provide

. additional information with reepect to the samples taken on April 26, 1991.

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SCH/ajs ZDESIGN/496-4

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i Attachment C Byron Station - Unit 1 DETAILED EVALUATION OF SAMPLE RESULTS FOR SUPPLEMENT TO THE JUSTIFICATION FOR CONTINUED OPERATION FOR LIMITORQUE VALVE OPERATORS THAT HAVE INDICATIONS OF CEEASE MIXTURES Introduction In November,1990, several Limitorque valve operators were identified as having a lithium based grease (believed to be Sun 50 EP) mixed in with the intended Exxon Nebula EP1, the main gear case lubricant. On April 26, 1991 and May 3, *991 the grease in five of the six affected operators was resampled to determine if any change in the grease properties was occurring. The results of the resampling is shown in Attachment B. The sixth valve, ISI88080, was not sampled due to ALARA considerations.

The effect of mixing small quantities of Sun 50 EP into Exxon Ne5ula EP1 ve s evaluated based upon

1) The as-found condition of the grease.

2) The results of ASTM D-1403 (1/4 scale) penetration testing performed in comparison to such testing performed previously on mixed grease samples.

As discussed in the EPRI NP-4916 " Lubrication Guide" the mixing of different lubricants can result in incompatibility, caused by interaction of the grease gel structures. Incompatibility is denoted by a distinct chanRe in the ASTM vorked penetration. EPRI NP-4916 defines a change in penetration of one NLGI grade or more as the point which, if exceeded, indicates that increaseo attention and possible grease change-out should be considered.

Evaluation The following provides an evaluation of the samples of grease taken.

a) Ouantity of Sun 50 EP Mixed with Exxon Nebula EP1 The quantity of Sun 50 EP mixed with the Exxon Nebula EP1 showed some percentage difference to the samples taken in November, 1990. This is considered to be normal. Though the grease is essentially uniform, (ie, well mixed) the overall volume of grease is not considered to be a complete homogeneous mixture. Accordingly, two samples taken at two different times may give different results. It is, therefore, expected that some difference vill occur from sample to sample. In comparing penetration test values, the percentage of Sun 50 EP does not by itself appear to be a contributor to differences in penetration test values. Accordingly, the recent sampling does not change the status of the grease as determined in November, 1990.

i SCH/ajs ZDESIGN/496-5

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b) Results of Senq9.12_IA82tetion the sampling of grease was performed in accordance with Byron j Procedure BTP-rS 28. The results of the sampling showed that the grease had no contaminants or water. Also, there was no indication of significant bleeding (ie, separation) of the oil from the gel. ,

The samples did not have a " burnt" odor, which would be an indication of oxidation. The samples had a consistency of new grease. Basto on these visual examinations, tho conditon cf the gresse is not changing.

c) Etlylis of ASTM _Pinetration Testa ,

The following summarizes the results of the penetration tests in connarison to the normal temperature and radiation environments of the alves, and in comparison to the percentage of Sun 50 EP.

Normal.S&Djitions Max %

ASTM D-1403 Penetration (w2rked)

_ Valve _ November 1990 API 11 26 1991 h 3 1991 Iemp. Radiation _ Sun 50 EPaa ICS009A 328 339

• 87.6'r 5 x 10 6 17x ICV 112B 294 279 298 107.6'T 6 x 107 20%

ICV 112E 305 253 310 118'T 5 x 106 10%

IS18801B 305 332 334 118'T 5 x 106 5%

! 1S18808C 287 *

• 107'T 9 x 106 e 317 313

• 130'T 5 x 106 7x 1S18809B

• No sample taken .

• • Quantity of Sun 50 EP from April 26, 1991 samples 1 On April 26, 1991, 5 of the 6 valves were resampled. The five valves sampled were ICV 112B, 1CV112E, ICS009A, 1518809B and ISI88018. The results of the l

ICV 112E sample was lower than expected and inconsistent with the sample taken in November, 1990. This sample was also inconsistent with the April 26, 1991 nample taken from 1S18801B, Vhich is located in the same temperature and radiation environment. The sixth valve, 15188080 was not sampled due to ALARA '

considerations.

To verify the accuracy of the results for valve 1CV112E, that valve, plus valves'1CV1128 and 1518801B, were resampled on May 3,1991. The initial sample from valve 1CV112E most likely had a' higher concentration of the thicker, less worked-grease which had been f9rced to the outside of the gear

!- drive casing. Once the initial samples were removed, access to the grease

- further-in-the sear casing was possible. As a result, the sample taken on May-3,1991 for valve ICV 112E is considered to be representative of the grease in that valve.

SCH/aja-ZDESIGN/496-6

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The representative penetration values for all valves range from 298 to 339, while the penetration values for NLGI Grades 1 and 2 are ASTM NLG1 Penetration gg _(vorked) 1 310 - 340 J 2 265 - 295 The testing shows that the grease has a consistency of an NLGI Grade 1 or 2, with a Grade 1 being most representative of the grease. Exxon Nebula EP1 is a Grade 1 grease. The grease mixtures are maintaining a consistency that is the same as 100% Exxon Nebula EPl.

ggnslusion The valves of concern, with the exception of valve ISI8808C are located i outside of the primary containment. A comparison of the normal, abnormal, and accident temperatures shova that the accident temperatures do not differ significantly from the normal / abnormal conditions. The existing grease has been installed for at least five years. Based upon the sensory inspection and penetration test results, no noticeable deterioration is occurring.

Extrapolating these results, NED concludes that no significant deterioration vill occur prior to the next refueling outage scheduled for September 1991.

Accordingly, the conclusion made in November, 1990 regarding the acceptability of the grease '.emains the same and the grease continues to be acceptable to perform its intended lubrication function.

SCH/ajs ZDESIGN/496-7