ML20066C178

Conveys Most Recent Info Re Util Position on Environ Qualification of Grease Mixtures Present in Some Limitorque motor-operated Valve Gear Cases at Byron.Tables Listing Results of Penetration Tests Encl

ML20066C178
Person / Time
Site:	Byron, Braidwood
Issue date:	11/21/1990
From:	Checca A COMMONWEALTH EDISON CO.
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
Shared Package
ML20066C180	List: ML20066C178 ML20066C185
References
ID628, NUDOCS 9101090332
Download: ML20066C178 (5)

Text

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Ctmmtnwealth Edison i '

l._ } 1400 Opus Plac9

'\ Downers Grove. Illinois 60515 November 21, 1990 Dr. Thomas E. Murley Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Attn: Document Control Desk

Subject:

Byron Units 1 and 2 Braidwood Units 1 and 2 Environmental Qualification of Grease Mixtures in the Main Gear Case of Limitorque Operators HRC_QQLLt.Ltios. 50-45A/A51JL52-151L451

Reference:

(a) June 23, 1988 letter from S.C. Hunsader to Dr. T.E. Murley conveying grease mixture test results (b) August 26, 1988 letter from S.C. Hunsader to Dr. T.E. Murley conveying grease mixture test results (c) November 22, 1988 letter from S.C. Hunsader to Dr. T.E. Morley containing an assessment by Dr. R. Bolt

Dear Dr. Murley:

The purpose of this letter is to convey the most recent information available regarding Commonwealth Edison's position on the environmental

-qualification of grease mixtures present in some Limitorque motor operated valve (MOV) gear cases at Byron Station. The letter of Reference (a) provided testing results requested by the NRC staff as a result of environmental qualification concerns arising from grease mixtures present in Braidwood Unit i valves. Additional testing results were provided for NRC review in the letter of-Reference (b). The test results provided the basis of an operability judgement made for eight Braidwood Unit i valves found to contain grease mixtures of 12% to 33% of Sun 50 EP mixed with Exxon Nebula EP-0/EP-1.

The letter of reference (c) included relevant information regarding; 1) the grease's physical properties, 2) the testing to verify those properties and 3) the impact of changes in the properties on the grease's lubrication function.

It is included as Enclosure 2 for ease of reference.

Enclosure 1 is an internal Commonwealth Edison Company (CECO) memo summarizing the Nuclear Engineering Department's engineering evaluation and conclusions regarding the acceptability of grease mixtures of 1 5% Sun 50 EP contained in Exxon Nebula EP-0/EP-1. References (a) and (b) contained test results which are summarized in this enclosure.

/scl:ID628:1 6 9101090332 901121 L ADOCK 0500( g,4

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l Dr. Thomas E. Murley - 2 - November 21, 1990 The environmental qualifications of the Exxon Nebula EP-0 and EP-1 is not compromised by the addition of 2% and 5% of Sun 50 EP. Test results and j visual examination indicated little difference in performance between pure Nebula EP-0/EP-1 and mixed grease samples containing up to and including 5%

Sun 50 EP. The Exxon Nebula EP-0 and EP-1 remains environmentally qualified consistent with the Limitorque requirements, Therefore, there is no need to replace the grease of Limitorque operators containing mixed grease samples of up to and including 5% Sun 50 EP.

Currently, six valves at Byron Station Unit I have grease mixtures in excess of 5%. It was determined that a Justification for Continued Operation (JCO) was required for these valves. Documentation of the JC0 was supplied to Byron Station by the CECO Nuclear Engineering Department by letter dated November 5, 1990 and was immediately made available to the NRC resident inspector for review. Changeout of the grease mixtures in these valves will be accomplished no later than the next refueling outage for Byron Unit 1.

Sampling-and testing of these six valves will be performed on a six month frequency to assure no significant degradation of the grease occurs until changeout. Results will be provided to the NRC after sampling and analysis is complete.

Additional documentation is available at Byron Station and/or CECO Nuclear Engineering and can be supplied upon request. Please direct any questions you may have concerning this matter to this office.

Very truly yours, h/ A.R. Checca 2V-Nuclear Licensing Administrator Enclosure cc: Resident Inspector-Byron Resident Inspector-Braidwood T, Shia-NRR R. Pulsifer-NRR Regional Administrator-RIII

/scl:ID628:2

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• Enclosure 1 P, .

158908 November 7, 1990 To: T. J. Kovach

Subject:

Byron Units 1 and 2 Braidwood units I and 2 '

EQ of Mixed Grease in the Main Gear _ Case of Limitorque Operators

References:

June 23, 1988 Letter from S. C. Hunsader to T. E. Murley.

regarding Braidwood Unit 1 Limitorque Operator Lubrication. ,

The following provides a summary of the Design Support EQ group evaluation of the effect that mixing small quantitles of Sun 50 EP with Exxon' Nebula EP-0 or EP-1 has upon the environmental qualification of the EP-0 or EP-1

-main gear _ case lubricant used in Limitorque operators. As discussed below, >

mixtures of Sun 50 EP that do not exceed 5%, have been evaluated to-determine:the affect on the environmental qualification of the EP-0 and EP-1

- for Limitorque operators at the Byron and Braidwood_ Stations.

Lubricants that can be used in the Limitorque actuators are identified in the appropriate instruction manual and Lubrication Data form LC8. The main gearboxes were originally tested and supplied for in-containment-applications with. Exxon Nebula EP-1 grecsc. Nebula EP-0 is now supplied for in-containment appitcations, although Nebula EP-1 can be mixed with or used in place of the EP-0; Limitorque does not recommend mixing the Nebula EP-0 and EP-1 with any other type lubricant.

As a result of the identification of grease mixtures-In Limitorque Operators at Braldwood Station in Harch, 1988, PHR Engineering estabitsbed a. testing-program to determine the effect of mixing different quantitles of Sun 50 EP with Exxon' Nebula EP-0.and EP-1. This was accomplished by comparing the physical properties of Exxon Nebula EP-0 andLEP-1-containing in each case 2%

and 5% Sun 50 EP against the physical properties of pure Exxon Nebula EPO and EP-1. To evaluate the effect upon. environmental; qualification,.the test

' program subjected samples of mixed and unmixed grease to. radiation

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environments of 2-x.10E5 and 2 xul0E8 Rads. During May and June', 1988, samples were radiation tested at Hyle Labs. ASTH D-1403 Penetration tests were_ performed before and after testing-to measure changes in consistency of

- the grease mixtures. Dropping point measurements (the temperature at which-the first drop offfluid separates from grease in a standard-apparatus) were also made, i

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Any' sample in which the worked' penetration values, between mixed and unmixed

. samples, which resulted in a change of less than 30 points were considered to be compatible based on the following:

a) The EPRI NP-4916 " Lubrication Gulde" which defines compatibility as "a change of-nqJAon_th6LL30_DRin11 (1 point = 0.1mm) in ASTM worked penetration on mixing."

b) The NLGI definition of incompatibility which states:

"Two lubricating greases.show incompatibility where a mixture of the products shows physical properties or service performance which are markedly inferior to those of either of the greases before mixing. Performance or-properties inferior to one of the products and superior to the other may be due to simple mixing and xquid not be consMentas evidente_of incomoatibility."

The tables below show the results of penetration tests for mixtures containing 2%_and 5% Sun 50 EP with Exxon Nebula EP-0 and EP-1.

Exxon Nebula EP-0 Worked Peneingtlon ASTM D-1403*

Radiation 2% Sun 51 Sun lxp.olure_._ 100% EP-0 M% EP Cttegg 95L.EP.0_ __ Chang e_.

0 395 395 0 392 -3 l_ 2 X-10E5 -362- 388 +26 388 +26 L

2 x 10E8 407 410 +3 407- 0 Exxon Nebula EP-1 Worked Penetration 60 Strokes ASTM D-1403*

Radiation 2% Sun N ' Sun

_Expolute 100% EP-1 _ElP- 1 Change E EP-1 .Jhuge_,

0 327 339 +12 332 +5 2 x 10E5 309 328 +19 324 +15 2 x 10E8 395 407 +12 407 +12

• Penetration valves provided are converted to full scale (ASTM 0-217) l penetration values, l

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l In all cases, the penetration results are within the EPRI NP-4916

" Lubrication Guide" criteria of no more than 30 points difference indicating compatible'gisase, when compared to 100% EP-0 and 100% EP-1 at radiation levels of zero, 2 x 10E5, and 2 x 10E8 Rads. The penetration values of the mixtures change (either up or down) in a similar fashion as the 100% Exxon product.

Overall, the_ test results show that under environmental conditions of zero, 2 x 10ES, and 2 x 10E8 Rads, mixtures of 2% and 5% Sun 50 EP in Exxon Nebula EP-0 and EP-1 will not.lmpact the lubricating qualities of the Exxon product. This continues to allow the Limitorque operator to operate and perform its intended function. As a result, the environmental qualification of the Exxon Nebula EP-0 and EP-1 is not compromised by the addition of 2%

and 5% of Sun 50 EP, The Exxon Nebula EP-0 and'EP-1 remains environmentally quallfled consistent with the Limitorque requirements.

For. assessing the effects of thermal aging on mixed grease, drop point and penetrant testing of the samples was evaluated. These tests, following thermal aging, Indicate that the mixed and unmixed greases perform similarly. Thus, there is no effect on thermal performance of the grease with the presence of Lithium. Since the lubricating performance has been demonstrated to follow the same trend of degradation as that of pure Nebula EP-1, the qualification testing performed by Limitorque on Nebula EP-1 is not compromised by the presence of Lithium in the mixed grease cases.

There has been no visual indication of a chemical reaction taking place as evidenced by normal consistency, and the absence of hardening, softening or separation. During sampling, the station utilizes BFP FS-28 to record data on the general consistency, color, presence of foreign matter (contalminants), and water. This data is recorded on BFP FS-28-T1. As a result of Fuel Handling Foreman Review there have been no abnormalities noted with respect to the above variables for all valves with the exception of two. Those-two, which had Indications outside the norm, were then chemically analyzed and found to have less than 2% Li content. It can be concluded from the visual results. documented, that no chemical reaction is taking place in the gear box which-would lead to premature hardening or

-softening of the grease. These valves have all been in service for a minimum of 5 years at Byron.

Should you have any questions, please call me at Ext. 7492.

S. C, Hunsader C hem M Corporate EQ Coordinator Design Support Group 20ESIGN/230 SCH/bim cc: N. P. Smith T. Schuster

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