ML20153G818
| ML20153G818 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 08/26/1988 |
| From: | Hunsader S COMMONWEALTH EDISON CO. |
| To: | Murley T NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8809080406 | |
| Download: ML20153G818 (11) | |
Text
/
N Commonwealth Hieon
/ C4 Fast Neuonal Plaza. Chicago, L5nois J Address Reply to; Post omco Box 757 O
sy CNcago, lihros 60600 0767 August 26, 1988 Mr. T. E. Murley Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Nashington, DC.
20555 Attna Document Control Desk Subjects Braidwood Unit 1 Limitorque Operator Lubrication tulC_.Desitt Mo 1Qdin References (a) April 22, 1988 S.C. Hunsader letter to T.E. Murley (b) NUREG-1002, Safety Evaluation Report, Supplement $6, dated May, 1988 (c) June 23, 1988 S.C. Hunsader letter to T.E. Murley Dear Mr. Murley Reference (a) identified four (4) valves that potentially could be exposed to radiation values greater than 2 x 107 rad. These valves are i
j 10G057A and 1RY8000A (inside containment), and ICV 1128 and 1CV112C (outside containment).
In order to show that the operators for these valves will function as intended, reference (a) indicated that a qualification test of a l
representative grease sample would be performed and completed within 60 days l
from the date Braidwood Unit 1 enters Mode 2 which occurred on April 24, f
1988. Reference (b) provided the NRC staff's review and evaluation of this submittal.
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Reference (c) informed the NRC staff that this testing had been completed with the results being provided in Attachment A to that letter.
l The samples of Exxon EPC/ EPI mixed with Sun EP50 had maintained a consistency whereby the lubricating capability had n't been reduced. Under o
a radiation exposure condition, it was verified that the grease will perform its intended function.
l During the reviews performed of mixed grease samples eight (8) valves were found with mixtures of 12% to 33% of Sun EP50 mixed with Exxon Nebula EPO/EP1. Additional grease mixture testing was performed that envelopes these cases. The results are presented in AttacMent A.
In these cases the mixed grease maintained its lubricating capability and as such was verified that it will perform its intended function.
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Y 8809080406 880326 L i PDR ADOCK 05000454 I
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-2 This is being provided for NRC review.
Please address any questions concerning this matter to this office.
Very truly yours,
- (.
S. C. Nunender Nuclear Licensing Ablaistrator
/klj cca S. Sands (NRR)
W. Torney (RI!!)
Braidwood Resident Inspector 4845K l
k._____-.
m--------
Ja kiroutt4 During the 1988 E.Q. audit of Braidwood Station by the NRC, several Limitorque operators on safety-related and non safety-related valves were found to have mixtures of srcase with different soap bases. Under cover of a June 23, 1988 S.C. Hunsador letter to T.E. Muricy Comonwealth Edison provided to the NRC the results of the light mixtures (2% to 5% by weight) of unqualified grease in the base grease.
Eight valves were found to have a heavy mixture (12% to 33% by weight) of unqualified grease in the base grease.
Seven of these valves had the grease changed out prior to unit startup.
The grease in one valve, a loop isolation valve, was not changed out and is discw sed further in the operability assessment section of this report.
Since eight (8) valves were found to have a heavy mixture (12% to 33% by weight) of unqualifed grease in the base grease, additional grease mixtures were tested to address the significance of operation of these eight valves while they contained the grease mixture.
This report first discusses the additional grease testing and the results of that testing and then addresses the operability of the valves whlie they contained the heavy mixtures of grease.
Saeple Description Forty samples of Exxon EPO and EP1 gresses (qualified) were penetration touted in accordance with ASTM D-1403, after mixing with 25%, 50%,
and 75% (by weight) of SUN 50 EP grease (unqualified).
Further, Exxon EPO was mixed with 25%, 50%, and 75% (by weight) of Exxon PPl.
Dropping point for many of the mixtures was determined in accordance with ASTM D-566.
These tests were perforned to define the characteristics of heavy mixtures of greases with different soap bases before and after irradiation as well as the effects of radiation on mixtures of Nebula EPO and EP1 (same soap base).
Table A shows the mix ratio of SUN 50 EP grease with Exxon Nebula EPO. The effect on the dropping point (if tested) and penetration value for each sample is also shown.
Table B provides the same information as in Table A for mixtures of SUN 50 EP grease with Exxon Nebula EPl.
Table C identifies the effects of radiation exposure on the penetration value and dropping point for heavy mixtures of Exxon Nebula EPO grease with Exxon Nebula EP1 grease.
Each of these tables also includes the effects of irradiation on the pure greases used in the mixtures.
Table 2 from the June 23, 1988 submittal showing radiation effects l
on the light mixture grease characteristics is also included for ease of reference and comparison.
6ppearance One sample, the 25% SUN /75% EP1 mixture that had been irriadiated to 5
2x10 R, appeared quite dry prior to working. Upon working, its appearance and consistency were no dif ferent from the unieriadiated sample.
The appearance and consistency of all other mixtures remained unchant,e3 f rou that of the unieradiated samples af ter exposure to both 2 x 5
8 10 R and 2 x 10 R gama.
Data' Interpretation - Heavy Mixtures A.
SUN /EPO Mixtures (Table 3)
Unteradiated mixtures, including the 50/50 mixture, show virtually no change in penetration from the pure SUN grease. The unirradiated mixture of 25%
SUN /75% EPO is approximately midway between pure unieradiated samples of SUN and EPO.
The penetration values for the heavy mixtures of SUN and EPO show minor changes between 0 and 2x105 R when compared to the unirradiated mixture.
8 Exposure to 2x10 R shows penetration values between 392 and 407 for both the pure SUN and the mixtures.
This is virtus11y identical to the results of the light mixtures shown in Table 2.
Some changes in dropping points were observed but this is only 8 R significant for 2 mixtures, the 75% SUN /25% Epo and 50% SUW/50 EPO after 2x10 0
0 exposure. The dropping point decreased to 285 F and 275 F, respectively.
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B.
SUN /EP1 Mixtures (Table 4) i The unieradiated penetration values for pure SUN and pure EP1 are very close (309 SUN. 328 EP1). None of the unirradiated heavy mixture penetration values show significant change from pure SUN grease.
l Modest sof tening of all mixtures was observed upon exposure to 2x105 R with the exception of the 25% SUN /75% EP1 mixture. This mixture showed significant stiffening, exhibiting penetration values of a Grade 3 grease.
Exposure to 2x108 R caused softening in all mixtures (the 75% SUN /25%
EP1 was softest at a penetration value of 395, which is coeparable to the light mixtures shown in Table 2.
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The 25%/75% mixture softened to a value that is virtually identical to unirradiated pure SUN grease.
Significant dropping point change is apparent for only one mixture, the 75%/25% after 2x108 R exposure. The dropping point terperature decreases to 295F j
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C.
EP0/EP1 Mixtures (Table 5) 5 Only minor changes in penetration values occurred froa O to 2x10 R for all mixtures.
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All mixture penetration values were in the 3$2 *e J10 ran6e aitar l
8 exposure to 2x10 R.
This is consistent with the light
' result 9 shown 'er Table 2.
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l No changes in dropping point for any of th-
'bserved.
- pperability Assessment six of the eight valves identified with heavy grease mixtures are identified in Table D below with the mixture ratio. E.Q. Zone, expected radiation field and temperature. All of these six valves are located outside the containment in the auxiliary building.
Table D Ratio Valve Nebula / SUN E.0. Zone Radiation Ie! e m
4 0
1AF017A A8 (mild) 1 x 10 R 140,
0 7
130 F (max) 1CV8355C 7:1 A13C 1 x 10 R 7
0 l
2CC9412A 3:1 A13C 1 x 10 R 130 F (rax) 7 0
l 2CV8355B 2:1 A13C 1 x 10 R 130 7 (max) 7 0
130 F (max) 2CV8355D 3:1 A13C 1 x 10 R 0
7 130 F (max) 2218920 4:1 A13C 1 x 10 R The grease mixtures tested (3:1 or 75% Nebula /25% SUN and til or 50%
Nebula /50% SUN) bound the worst mixture found (2:1 or 66% Nebula /33% SUN).
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Since, after exposure to 2 x 10 R and 2 x 10 R, all grease mixtures tested l
had the apperance, consistency, and penetration values characteristic of 0
I grease and dropping points of 275 F or greater, all six of tbase valves were l
operational while containing the heavy mixture of grease.
Valve IRC 8001 A is a main loop isolation valve that is power locked out during all operational modes, power is restored only during shutdown to l
expedite WSSS maintenance. This valve serves no safety function beyond l
maintaining the pressure boundary, thus operability and E.Q. qualification are I
not issues. The grease in this valve has not yet been changed out.
Valve ICC9438 is the inboard containment isolation valve for the component cooling return line from the number 1 seal on the reactor coolant pumps. This valve closes within 10 seconds of receipt of a phase 5 containment isolation signal (FSAR Table 6.2.-58).
Assuming a loss-of-off-site power coincident with the 1.OCA/MSLB, the valve will recalve the isolation signal 22 seconds after the initiation of the event (Tech. Spec.
Tables 3.3-5 and 3.6-1).
Therefore, operability of the valve for 32 seconds after initiation of the event is necessary.
0 From FSAR Figure 6.2-14, the containment temperature reaches 275 y I
approximately 30 seconds after the initiation of the MSLB. At this time 4
(accident only) radiation exposure has reached approximately 1x10 Rads.
AlsofromTSARFigure6.2-14, the containment terparature reaches approximately 300 F, 40 seconds af ter the initiation of the MSLB while 4 Rads. The worst caseradiationexposurelevelfor300gproximately1x10 radiation exposure level remains at a F containment temperature 40 seconds 5 Rads. This radiation exposure j
after MSLB initiation is approximately 6x10 level considers a normal 3 year dose plus accident.
By vicu 1 cbs:rv ticn. o ge:cco cixturo was id:ntified in the valva Limitorque grease box. Using Atomic Absorption Sepctroscopy ( AAS), the ratio of the grease mixture was determined to be 33% SUN with 66% Nebula. Physical data from the heavy mixture test program shown the worst overall mixtures (25%
SUN /75% EP1 and 50% SUN /50% EPO) to bound the mixture actually contained in the actuator.
The 25% SUN /75% EP1 mixture stiffens to the consistency of a grade 3 grease after exposure to 2x10 R garma,0then softens as exposure increases to 8
2x10 R gamma.
A dropping point of 446 F is maintained as radiation exposure increases.
This high dropping point ensures lubrication will be maintained around the worm gear during and after an accident. The heavier grease grade is judged to be insignificant in that the worm gears will perform equally well regardless of whether a heavy or a lighter grease is used.
The 50% SUN /50% EPO srease mixture displays a decrease in dropping 0
5 point to 315 F af ter exposure to 2x10 R while maintaining a penetration valve consistent with tha unirradiated grease. As described above, 0
containment temperature is 300 F after 40 seconds. Since the worst case 5
SUN /50%EPOmixturewouldremainatapproximately315gointforthe50%
radiation level at this time is 6x10 R, the dropping F.
This ensures that lubrication in the form of grease would be maintained around the worm gears for the 40 second time required to operate this valve assuming a loss-of-of fsite power coincident with a LOCA/MSLB.
It is concluded that no detrimental effect on the operability of any of these eight valves is caused by having heavy mixtures of SUN 50 EP grease with either Nebula EPO or Nebula EP1 grease in the Limitorque operator gear 1
box.
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Table A Penetration Oropping Point Mix Ratio Red. Levet ghed Unworked
'C/ F (D-566) 1008 $UN 0
309 294 183/M2 2x10 320 298 177/35l 8
2x10 407 328 IM/M9 4
i 796 $UN/295 EPO O
292 270 165/328 f
2x10' 343 324 150/302 I
2x10 392 358 140/295 l
[
4 SOS $UN/508 EPO 0
314 309 173/M3 2x10' 301 245 157/315 I
2x10 407 328 135/275 l
l 236 $UN/795 EPO 0
354 347 230/446 l
2110' 324 257 230/446 t
2x10 403 287 230/446 o
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1005 EPO 0
344 230/446 5
l 2x10 230/446 l
2x10 230/446 t
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i Penetration Dropping Polnt i
Mined Ratto.
Red. Level W
jnworked
'C/'F 1005 $UN 0
309 294 183/M2 l
f 2x10' 320 298 177/351 2x10 407 328 IM/M9 795 $UN/295 EPl 0
292 279 164/334 2xt0' 339 283 151/304 2x10 395 373 146/295 l
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505 $UN/505 EPl 0
310 294 230/446 l
2xl0' 34 3 324 230/446 2xt0 369 223 158/316 l
l 1
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295 $UN/795 EPl 0
296 283 230/446 l
2x10' 241 159 230/446 f
2x10*
305 200 230/446 1005 EPl 0
328 230/446 5
4 2x10 309 309 230/446 i
2x10 395 377 230/446 4
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l Table C Penetration Dropping Point Mix Ratio Bed M tierked Unworked
'C/'F g-jti),
100ENobule EPO 0
344 230/446 2x10' M2 M2 2M/446 1
2x10' 407 399 2M/446 905 EP0/25 EPl 0
354 2M/446 2x10' M4 373 2M/446 tulo 410 410 2M/446 996 EPC/95 EPl 0
300 230/446 2x10' 377 373 230/446 2xl0 410 410 230/446 L
795 EP0/295 EPl 0
373 230/4%
2x10' 373 369 230/446 I
2x10 410 407 2 M/446 Sol EP0/ Sol EPl 0
3M 2M/446 2x10 M9 3S4 230/446 2xl0 392 392 2 M/446 i
295 EP0/7M Eri 0
347 2 2/446 l
2xt0' 339 3M 230/446 2x10 403 399 OM/44
l Tablo C (Cent'O a
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l Penetration Oroppling Point Nim Ratte W. Level M
Unverhed
'C/*F (0 966)
I 95 EP0/998 EPl 0
324 230/446 blo' 320 3M 230/446 2ml0*
M2 M2 230/446 i.
25 EPC/995 EPl 0
324 230/446 2x10' 309 3M 230/446 2ml0*
410 399 230/446 r
IDJE EPl 0
328 230/446 2ml0' 309 309 230/446 2x10 395 377 230/446 i
I4$20 I
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Dropping Point I
Penetration (D-14038)
+
lample Min. Matto fted. Level Worked Unverhed M(D-SM) e t
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BIA 26 Sun /985 EPO 0
M2 MS 2M 82A 2m10%
M4 Me 2M i
8 SM 2ml0 R 410 410 230 tit 3 Svv988 EPt 0
3M 3M 230 r
BB 2ml0%
320 3M 2M f
BM 2m10%
407 407 230 SIC M Swn/996 EPO O
MS M2 230 f
B2C 2m10 R M4 MS 22 i
5 B3C 2ml0 R 407 407 2%
f 0
SID M Sun /995 EPl 0
328 332 230 I
820 2ml0%
328 324 230 330 2x10%
403 407 230 f
t heferonce f
i 1006 EPO 0
M4 (Actual Valwe) 2M 2
1005 EPl 0
3 M (Actual Value) 230 3
1006 LP0 0
370 (Monf. Spec.)
230
[
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1005 EPl 0
3M (Ment. Spec.)
230
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- Converted to full scale (ASTM O-217) penetration values.
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