ML18092B435

Responds to Violations Noted in Insp Repts 50-272/86-23 & 50-311/86-23.Corrective Actions:Attachment B-2 Revised to Correct Misinterpretation of Grease Clogged Drains.Revised Attachment B-2 Encl

ML18092B435
Person / Time
Site:	Salem
Issue date:	02/13/1987
From:	Corbin McNeil Public Service Enterprise Group
To:	Heishman R NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
References
GL-86-015, IEB-84-44, NLR-N87017, NUDOCS 8702260252
Download: ML18092B435 (7)

Text

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Public Service Electric and Gas Company Corbin A. McNeill, Jr. Public Service Electric and Ga? Company P 0. Box236. Hancocks Bridge. i\JJ 08038 609 339-4;300 V:ce Pres*cen:

• February 13, 1987 NLR-N87017 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Attention: Mr. Robert F. Heishman, Chief Vendor Programs Branch Division of Quality Assurance Vendor and Technical Training Center Programs Off ice of Inspection and Enforcement Gentlemen:

NRC INSPECTION 50-272/86-23 AND 50-311/86-23 REVISED RESPONSE TO INSPECTION REPORT SALEM GENE~TING STATION DOCKET NOS. 50-272 AND 50-311

~ meeting was held on Fe~ruary 3, 1987 at NRC Region I to discuss our responses to those Salem EQ inspection findings subject to the 10CFR50.49 enforcement criteria delineated in Generic Letter 86-15. During the meeting, NRC staff representatives were notified of changes to our previous responses (dated November 7, 1986 and December 15, 1986) to the subject inspection report.

Those changes are being formally submitted by this letter and its attachment.

We first request that our previous response to Potential Enforcement/Unresolved Item 50-272/86-23-03: 50-311/86-23-03 regarding the qualification of Rockbestos EPR and Coaxial cahle be withdrawn. An in-depth review of our November 7_, 1986 response to this finding was performed by PSE&G prior to the meeting at NRC Region I. The results of the review determined that although PSE&G EQ personnel were knowledgeable of the additional tests which substantiated the results of the questionable Rockbestos test reports noted in IE Information Notice 84-44, these test reports had not been formally analyzed and referenced in the Rockbestos EQ file. As such, the inspection finding in this area is not disputed.

The review of the response to Potential Enforcement/Unresolved Item 50-272/86-23-04: 50-311/86-21-04 also uncovered certain discrepancies in the information presented with regard to the Limitorque gear case grease reliefs. Correction of these

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. ' Document Control Desk 2 2/13/87

• discrepancies does not alter our position that tha grease reliefs were not required for the operability of the Limitorque operators in containment under Salem plant-specific post-accident conditions.

The statement in Attachment B-2 to the November 7, 1986 letter with regard to the reasons for the clogging of the drains in FIRL Test Report F-C3441 were misinterpreted in that the drains were clogged with grease which had come out of the grease relief valve after the flooding of the test chamber. The grease actually came out of the relief valve prior to the flooding of the chamber. The grease used was not identified. This misinterpretation does not alter the overall analysis performed on the subject item and has been corrected in the "Revised Attachment B-2."

The grease referred to in the November 7, 1986 submittal, Mobil Grease 28, is used in the intermittent gear box (not the main gear box) and is valid for that application. The intermittent gear box has no grease relief valve. The grease used in the main gear box is EXXON Nebula EPO or EPl. Although it is not a synthetic lubricant like Mobil Greas~ 28, it has been evaluated and the results indicate that it would perform in a manner similar to that presented for Mobil Grease 28. Analysis of the in-containment post-accident conditions with respect to the warming of the gear box and the subsequent expansion of the grease have indicated that appreciable expansion would not occur and that the ~witch compartment would not be breached.

Also, the statement in the November 7, 1986 submittal with regard to "appreciable expansion" of the grease only occurring afier reaching the dropping point should not have been interpreted to mean that no expansion occurs until the dropping point is reached. It is understood that expansion will begin to occur upon the initial warming of the grease. To avoid any confusion, this statement has been withdrawn. A Revised Attachment B-2 is provided with this letter.

Please contact Mr. Bruce Preston at 609-339-5129 with any questions you may have* Your cooperation in this matter is appreciated.

Sincerely,

• Attachment

Document Control Desk 3 2/13/87 C Mr. D. C. Fischer Licensing Project Manager Mr. T. J. Kenny Senior Resident Inspector Dr. T. E. Murley Regional Administrator Region I

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Revised Attachment B - 2 A potential enforcement item was identified by the NRC related to the absence of gear box grease reliefs on Limitorque actuators located in containment. The con~ention is that the gear box grease reliefs must be provided in the plant installation since they were installed in the Limitorque actuators subjected to the LOCA/MSLB test simulation. It is verbally stated by Limitorque that the relief valve provides for relief of grease and the pressure build-up which occurs due to thermal expansion at prolonged elevated temperatures.

However, Limitorque also states in Report 80~58, pages 14 and 15, that "Limitorque actuators for Nuclear Plant applications are designed to operate in normal and accident conditions without depending on absolute sealing. In fact, the ambient is not absolutely restricted from entering the actuator. The seals, are of no importance for qualification and, therefore, require no consideration for the qualification".

Mr. J. Drab of Limitorque stated in a telephone conversation with Ms. B. Horst of PSE&G on April 9, 1986, as documented in the Record of Verbal Discossions, "They are not an EQ require~ent and their absence does not adversely affect the qualification status of Limitorques", Mr. Drab and Limitorque have subsequently refused to issue this statement in a signed letter.

In FIRL test report F-C3441 prepared for Limitorque (used in their BWR Containment Report-60376A), it was identified that flooding of the test chamber occurred from a build up of steam condensate when the test chamber condensate trap became clogged.

This was attributed to a grease build up in the trap caused by grease that had evidently come out of the relief valve during the test. The test was stopped during the fifth day. Prior to the test discontinuation, the specimen had been subjected to 2, three hour transients at +340°F, 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> at +320°F and 4 1/2 days at

+250°F.

The Salem plant temperature profile for a Main Steamline Break (MSLB) shows a peak temperature of 347°F for 72 seconds, droppinq to approximately 260°F in less than 5 minutes. For a LOCA, a peak temperature of 268°F is reached and maintained for 12 1/2 minutes. Within 30 minutes the temperature will fall below 250°F. Each of these accidents produces a peak pressure of 43.2 psig for 170 minutes. Therefore, an external positive pressure is maintained for the duration of the temperature transient minimizing the pressure differential due to possible internal pressure buildup.

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' . The Superheat Temperature Test Report #B0027 was performed to determine the internal temperatures of components in the Limitorque valve actuators due to superheat ambient temperatures. It illustrates that exposure of the actuator to high environmental temperatures for short durations of time will not raise internal unit temperatures to an equal state. It was demonstrated by analysis that an*ambient temperature of 492°F in excess of 17 minutes would only result in a maximum internal temperature of 315°F for the electrical switch compartment components and motor windings. Actual testing indicates that an ambient temperature of 385°F was reached at 186 minutes and at this time the temperature inside the motor was only 282°F.

It can therefore be concluded that the effects of high ambient temperatures over a short time period will not result in excessively high internal temperatures. As such, excessive internal pressure will not result.

The grease utilized for lubrication of the intermittent gear box in the Limitorques at Salem is Mobil Grease 28. This. is a synthetic lubricant exhibiting high pressure characteristics at temperatures in excess of 350°F. This grease has a dropping point of approximately 500°F, which precludes its changing to a liquid state even under superheat conditions.

The main gearbox utilizies a calcium complex base grease manufactured by Exxon and known as Nebula EPl (or EPO). This grease can be used for applications up to 400°F, it contains an Extreme Pressure (EP) additive to help increase the film strength of the oil, and has a dropping ~oint of approximately 500°F. The EPl grease exhibits similar characteristics to the Mobil 28 grease and both types of grease are approved by Limitorque for in-containment applications in the operators.

In Test Report B0003, an actuator containing Nebula EPl gearbox grease was exposed to a sustained temperature of 250°F for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Grease relief valves were not installed on this actuator as Limitorque evidently determined that exposure to 250°F and 25 psig during an accident test was not sufficient to justify their usage ** The test unit actuator was a SMB-0 type, which is rather small, containing approximately 9.5 pounds of gearbox grease.

Larger actuat9rs contain up to 75 pounds of grease (SMB-4 or 5 type). Given the small size of the test unit, it can be deduced that maintaining the temperature at 250°F for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> will bring

.the entire unit to therma1 equilibrium, including the gearbox grease. It can therefore be determined that EPl type grease can be heated to 250°F and will not expand to any degree that would require the use of a grease relief on the actuator.

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... By utilizing the Salem accident profile for temperature and pressure for worst case Main Steam Line Break (MSLB) and Loss-of

-Coolant Accident (LOCA), it can be determined by analysis that exposure to either condition inside containment will not cause the gearbox grease to exceed 250°F. This is due to the fact that the maximum LOCA temperature of 268°F is reached in approximately 4 minutes following the start of the accident, after which the temperature slowly begins to decrease. Thirty minutes following the start of the event the temperature has fallen below 250°F.

As is evident, the time duration is not sufficient to heat the grease above 250°F.

During the MSLB event, a maximum temperature of 347°F is *reached in approximately 100 seconds. This temperature is maintained for 72 seconds, after which the temperature rapidly begins to decrease. Thirty minutes following the start of the event the temperature falls below 250°F. Again the time duration at the temperature above 250° is not sufficient to heat the grease above 250°F.

The characteristics of the grease would be a factor in determining the necessity of grease reliefs on the gear case housing. Since the greases utilized during the qualification tests were not identified, a correlation of actual parameters cannot be made. However, a temperature resistant grease such as the Nebula EPl appears to have been used.

As proven by test, the internal temperature of the operator, even un-der superheated ambient conditions, would not cause the internal temperature to exceed saturated conditions. This temperature is well within the design limits of the specified grease and would not be cause for it to exhibit appreciable expansion. A pressure buildup sufficient to breach tbe switch compartment is not possible under the Salem Station postulated accident conditions and therefore grease relief plugs are not required to maintain operability of the valve.

It should be noted that PSE&G's position was, and still is, that a determination to not use grease reliefs was made from all known and available information. Based on the verbal information from Limitorque, the Salem PWR specific accident profiles and knowledge of the data in the test report; it was determined that the grease relief valves were not necessary; would not prevent the valves from performing their safety function; and their absence would not be in violation of the qualification status of the actuators.

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For information purposes, at the time of the inspection, there were 7 in-containment class lE actuators in Salem Unit 1 that were identified by Station QA personnel as not having grease

• . relief valves. Salem Unit 2 had grease relief valves installed on all in-containment actuators. In accordance with the recommendation to. utilize grease reliefs as good engineering practice, grease reliefs are now installed on all in-containment actuators at Salem.

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