ML20066C185
| ML20066C185 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 11/22/1990 |
| From: | Hunsader S COMMONWEALTH EDISON CO. |
| To: | Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20066C180 | List: |
| References | |
| 5323K-1, NUDOCS 9101090337 | |
| Download: ML20066C185 (5) | |
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Chicago,Ilknois 60690 0767 November 22,-1988-Mr.~ Thomas E. Hurley, Director Office of Nuclear Reactor' Regulation
-U.S.. Nuclear Regulatey Commission-Washington,L DC 205b4 Attnt. Document' Control Desk-Subjectt' Braidwood Units 1 and 2 Limitorque Operator Lutlication HRC Docket No. 50-456 and 50-457-Referencet-(a).NUREG-1002, Safety Evaluation-Report, Supplement 46, dated May,'1988 (b)-August 26, 1988 S.C. Hunsader letter to T.E. Murley (c) September 2,_1988-S.C. Hunsader' letter to T.E. Hurley (d) October 6, 1988 S.P.--Sands letter to H.E. Bliss Dear Mr. Hurleyt To verify'that the as-found grease mixtures at Braidwood Station
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would have performed -their intended function, mixtures of SUN 50 EP and Exxon Nebula EPO/EP1 greater than.5% were. radiation tested.-
The results of_that testing'were provided to the NRC staff in references (b) and-(c).
It was Commonwealth Edison's (Edison) position that the samples of Exxon Nebula EPO/EP1 mixed with-SUN 50 EP had not changed enough to compromise the Limitorque's operating function. Under a radiation exposure condition, Edison believes =that the grense would perform its intended lubricating function.
In reference (d) the NRC Staff provided their evaluation af Edison's submittals,=and concluded that-there was insufficient information to make-a determination on the post accident operability of the Limitorque value:
. operators.
In response to this, Edison-requested that Dr. Robert O. Bolt perform an-independent: review-of references (b), (c), and (d), and give his
~ Attachment "A" provides the results of his review, which Edison assessment.
believes _ addresses the NRC Staff's~ concerns regarding operability. _In summary, Dr. Bolt states that for the worr'e-case sample presented in Attachment "A" to reference (b)r operability is not compromised by the harder grease since it in.
similar to that in other operators that have.been demonstrated to be operable-
.under similar irradiation conditions.
9101090337 901121 POR ADOCK 05000454 l
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T.E. Hurley 2-November 22, 1988 Please address any questions concerning this matter to this office.
Very truly yours,
, (. -
A S.C. Hunsader Nuclear Licensing Administrator
/ sci cc S. Sands-NRR J. Hinds-RIII J. Liebermann (Office of Enforcement)
Draidwood Resident Inspector 5323K-1
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.j ATTAclaiENT #A"
.a EVALUATION OF' EDISON sqKE) GREAEf_TRSTINQ BY Dr.
R.
O.
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The following provides a summary of a rtview of information ptovi-93
.in Commonwealth Edison letters dated August 26,.1988 and September 2. 1988,
'and in the NRC letter-dated October 6,.1988.
A, Data and Conclusions Recardino Grease Mixtures In the case of greases, the active ingredients for lubrication purposes l
are the oil together with its soluble additives.
The gelling agent that changes _an. oil into a grease acts with a " sponge" effect that releases the oil to the affected parts on demand. The additives in the oil enhance the lubricating properties of the oil.
For high quality lubes, these additives include-oxidation inhibitors, rust inhibitors, and load-carrying improvers (EP additives). The last two have been specifically required by.
Thermal and hydraulic stabilities are also required by Limitorque.
Consistency (penetration).and melting point (dropping point) _ values are not necessary. measurements of lubricating ability, but rather, are a means-
-to measure the. ability of!a lube to ramain in place.
In some
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applications, where retent. ion of the grease is necessary for lubrication purposes, this "remainingLin.placo" is very important.
- However, this is not as important in the case of Limitorque operators, because the lubricant is contained in a gear box which provides the retention function. When gear boxes are used, the most common lubricants are oils.-
Greases.have been specified by Limitorque in order to reduce leakage through seals, thus decreasing maintenance requirements.
The grenses Edison tested _J3s presented in the Auoust 26. 1988 1g(tgtl l
. hayp_these pr.2pertlen soocified above.
In fact, all the greases listed in EPRI NP 4916 (except for the three footnoted) have these properties and
- would meet Limitorque lubrication requirements. 'Tht Sun 50 EP is not listed because it is currently an obsolete product. However, it does-
. provide satisfactory. lubrication for this application.
The test results that Edison has obtained are what would be expected for
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-the greases tested (ie, an appreciable softening on radiolysis and-a tendency toward static-hardening (softening on working]).
Grease softening is of no significance with Limitorque operators, unless massive leaks take place.
Routine maintenance inspection would identify tlis problem so that appropriate action can be taken.
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2 There is an unexpected hardening of the mixtures at the 2 x 105 red dose for both Exxon Nebula EP-O and EP-1.
This af fect carries over to some of the rniatures that include SUN 50 EP.
The cause of the hardening is likely the N9bula product because the results of testing on the Sun 50 EP are as expected without noticeable hardening. There is no evidence of incornpatibility between the Sun 50 EP and the Exxon Nebula EP-0/EP-1 greases.
The 11tadiatio3LdocLnat_.Adnucly_.ntLecL_the lubricatism function,_nnIticularly at the_.Lel a t i v e l y_ lay._danc LsAen._i n_.the E d i snn its.th IhcLc_in_ Abundant evidente__(.EPRI NP 47M1.1hhL.1HAdifLt1QD 1mPLQXCA tht_ltad-earrylng capacity ef 1ublifAntL. Elight 911dat12ILtakts p10 AIL 11LLadiatiDILacC11cLates oxidation), forming _ polar companndg that-Enhance _1Mblicitt12n qualitith B.
Commenta_o2L11RC._Staf f Conclusinns The Nhc Staff raised a question on the offect of temperature.
A decrease in dropping point is evidenced in the test data in Attachment A when the Sun product is involved.
This would cause greases to soften and possibly liquefy if the dropping point is appreciably exceeded. The imposition of 3000P in the accident scenario would cause more fluidity because it would break down the grease gel structure.
As already discussed, this is not a problem with tim 1 torque operators because an oil lube will function acceptably in the gear box.
The sof tening of greases on irradiation has not been cited by the HRC staff as a problem with the Limitorque operators.
However, the hardening was cited by the staff as a problem with the key factor being whether the equipment will operate with this grease.
Thc.yorEL.casc_ hardening.II2ntthe_dnta ltLAtitchatnL A_to_the__AngusLE.
191fLtdison letter is_the 25% Sun /7 5% lithnin_Cf-1. mixtutc_alttI_capssqLe 5
tg_2.K 10 Inds.
The test results give penetration values of unworked (UW) 159/ Worked (W) 241.
A similar case has been observed from a penetration test result of W152 for grease from a Limitorque that was operating satisf actorily, but was taken out of service by Washington Public Power Supply System.
In this case, thickening of the grease was caused by a loss of the oil component. There was no significant degradation in chemien1 composition due to irradiation.
Also, a grease of UW 200/W 256 was taken f rom a Limitorque operator by Alabama Power because of an indication of mixture with another grense.
No equipment failure was involved (after some seven (7) years of operation).
Discussions of the above with Mr.
T. Cadlub of MOVATS, who has done maintenance work on Limitorque operatious, has confirmed many instances of ope ation with thick grea;es without failure of the Limitorque operators.
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3-These cases are examples of verifiable data illustrating the operation of Limitorques with thick greases.
In reviewina the test results from the August 26. 1988. Edison letter, the worst cas.t.hardenina condition is not
.gensidered:to be enouah to orevent the Limitorcue operators from functionina.
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