ML20054E074
| ML20054E074 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 03/20/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20054E068 | List: |
| References | |
| NUDOCS 8204260104 | |
| Download: ML20054E074 (7) | |
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UNITED STATES I
g NUCLEAR REGULATORY COMMISSION O
j WASHINGTON. D. C. 20555 o
%.....s SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 58 TO FACILITY LICENSE NO. DPR-35 1
BOSTON EDISON COMPANY PILGRIM NUCLEAR POWER STATION 1
DOCKET NO. 50-293 Authors:
.K.' Eccleston I
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H. Garg
- 0. Rothberg, I.
Introduction During previous cycles of operation, Pilgrim Nuclear Power Station was operated with higher than normal ambient drywell temperatures due to inadequate drywell cooling.
The temperatures experienced during Cycle 5 operation ranged as high as 2500F at the upper elevations of the drywell.
This evaluation addresses the effects of these higher than normal drywell temperatures on structures and equip-ment important to safety, and the. adequecy of the Technical Specification changes proposed by Boston Edison Company (the licensee) in its March _lm.l982 application to provide limiting conditions.for opera. tion and surveillance require-..
Mgegh drywell temperature and associated temperature monitoring II.
Background
On-September 26, 1981 during a routine shutdown for refueling, the installed Yarway water level instrumentation experienced oscillations. These oscillations have been attributed to flashing in the reference leg of these yarway instruments caused by the excessively high drywell temperatures.
By letter dated January-18, 1982 the licensee provided its evaluation of the effects of high drywell temperature operation on structures, components, and on transient and accident analyses. This evaluation also described the measures taken to correct or repair identified deficiencies and described the licensee's plans and programs for modifications and replacements to enhance drywell cooling capability and to assure equipment operability and qualification for at least one more cycle of power operation.
III.
Evaluation A.
Structural 1.
Drywell penetrations l
Drywell penetrations are designed for thermal expansion at a drywell temperature l
of 2810F, which envelopes the drywell temperatures experienced prior to and l
during the last cycle.
Consequently, no detrimental effects of th'ermal 82 0.4 26 0 /Dy l
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2 expansion on drywell penetrations would have resulted from operation with the maximen drywell temperatures experienced during previous cycles of operation.
2.
Differential expansion of the steel and concrete portions of the drywell The steel containment liner is mechanically attached to the concrete shell only in the lower regions of the drywell (lower 7 feet of the drywell). At these elevations the experienced drywell temperature was below the maximum drywell design. temperature; therefore, no adverse effects resulting from differential expansion of concrete and ' steel would have resulted from operation during previous cycles.
3.
Resistance of the drywell structure to jet impirigement. and other LOCA loads The Pilgrim Final Safety Analysis Report (Appendix L) containmerit stress analysis performed assumed target area temperatures of 300 F, which is the same 0
temperature as that of the impinging jet.
Since the drywell temp'erature did not exceed 3000F at any time, these analyses are not invalidated by the higher drywell temperatures experienced during previous cycles.
4.
O Effect of high drywell temperatures on drywell concrete strength
~The licensee has provided the results of analyses performed by itb consultant using published test data to determine residual concrete strength after cyclic heating.
The licensee states that these analyses indicate an average residual -
strength of the concrete closest to the liner of approximately 4500 psi and that this is conservative when compared to the actual computed stresses of less than 2000 psi.
Based on the margins available between required strength and analyzed strength, we find this acceptable for restart.
However, to provide long-term assurance that the concrete structure is capable of carrying its applicable loads, we will require that the licensee provide further confirmation of its evaluation by performing an analysis of the concrete structure assuming conservatively high temperature values and conservatively low concrete strength
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-through the wall.
B.
Equipment and Components Our evaluation of the individual components identified as being subject to the high drywell temperatures experienced is as follows:
1 1.
ASCO solenoid valve, model no. NP8320A184E i
Initial qualification testing of these valves was performed in a 268F ambient l
temperature with the solenoids in the energized condition. The manufacturer's catalog data indicate that energization of. the solenoids results in a 144F temperature rise above ambient.
Using this assumptioh, a thousand years would be expected for a deenergized valve. (qualified life of several the normal operating mode) in a 190F environment. However
~ f t}ie'sblenoid temperature r' ~s.,_even if credit is only_given for about one-half
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o i e as a result of energizatilin,'~the caliiiifaTe'd~
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remaining quafifTe~d ITfFbf"the' ASCO sol'enoids is more~than one operating cycle.~ "~~
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Consequently, we conclude that continued operation is justified.
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3 2.
AVC0 solenoid valves, model no. C5159 No aging test was performe'd on the subject valves but the licensee has provided a detailed aging analysis based on the Arrhenius methodology.
Based on this analysis the licensee has established that the qualified life of the subject valves is eight years.
However, based on more recent information from the licensee on March 19, 1982, the licensee stated that all nonmetallic parts of the subject valves have been replaced.
Based on this replacement, we find that c:ntinued operation is justified.
3.N NAMCO liinit sw' itches, modek rko EA740;501057 r
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The 1.icensee has performed the aging analysis and based on the analysis has replaced the Buna-N ~ gaskets and-EPR seals with new silicone rubber material for all affected limit switches. The licensee has alto indicated that both grease.and oil have a manufacturer'~s rating of 400F. to.500F and: therefor:e do _ _.
.not: require replacement.
Based on our evaluation of the licensee's ass'essment,
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we find ~ that' continued op#aMon is jiis~fifiiid.
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Target rock solenoid valves, model no. 1/2 SMS-A-01 The licensee h'as replaced the subject valves with new Target Rock solenoid valves that are qualified to IEEE-323,1974 and have a six-year manufacturer's_
recommended maintenance interval.
Based on this, we find that-continued-
" operation is justified.' ~.r
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5.. Limitorque valve actuators, model SMB-(various)
The licensee has performed an aging analysis and visual inspection and based on that has verified that (a) Viton seals are used in all M0V's, (b) melamine or fiberite has been used for the limit switch material, (c) jumper wires for M01001-63, M01001-50 and M01201-2 have be.en replaced, (d) all lubricants have b:en: replaced, and (e) new limit switch gear frames and limit switch compartment covers are on order and wil.1 be, replaced next refueling outage.
Based.on the above and since (1) Limitorque has: judged the limit. switch compartment. cover-acceptable for BWR operation and '(2) no visual corrosion effects were found on the. gear frames, we; find that continued' operation is justified. _
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TEC valve flow monitor system, model no.1414 The l'icensee has indicated that the charge converter and cable assembly are new units and the only component of this system which has been exposed to high drywell temperature is the accelerometer sensor. The licensee has indicated that the sensor does not contain any age sensitive material and the connector is manufactured from a silicate compound with an expected life of 147,548 years.
Based on our evaluation of the licensee's assessment, we find that continued ~
i operation is, justified.
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Junction boxes The licensee has performed the aging analysis and based on this analysis has replaced gasket material for all junction boxes above the 30' elevation with the new silicone rubber gaskets.
Gaskets below 30' elevation have a remain'ing expected life of 13.25 years at 1520F or qualified life of 4.4 years at 152 F.
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- Based on our evaluation of the licensee's~ assessinent, we find that' continued "
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operat!iofi is justified.
8 Ring tongue type termitiation,.,
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f souNi installa' tion ~pYactfces' i;o att'ach teminations' t'o 'a'qu,al'ified
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.The use barrier-type teminal block ~ assures that adequate c1'earance is provided. sow w :..,
that failure of the lug shank insulation would not impair circuit operability.
.The licensee has either installed new, qualified ring tongue. type teminations.
or, by. inspection, verified proper installation and that adequate clearance.
between connections has been provided.
Based on these considerations we find that co.ntinued operation is. justified.
9.
Kerite 600'V power and control. cable ' type FR/FR The licensee has taken two samples, one from the 41' elevation and another one n
from.th.e 73' elevation, and perfomed physical (elongation) and electrical tests.- Based on these tests.the licensee has listed the percentage elongation for s' ample 1 as 235 for the insulation and 250 for the jacket while for sample 2
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the percentage elongation was 110 and 160, respectively.
The licensee has also quoted the percentage elongation of 150 and 190 for the material aged to 40 years at 90C operating temperature.
Based on these numbers it is apparent that. sample 2 has lost more elongation than for the original test.
However, it should be 'noted that the original testing for radiation was tested for 200 Mrads.
while the expe.cted. post-accident _LOCA_ dose _is_.only 64_ Mrad._ _.This_ indica.tetthat_.the_ _.
_e_loncation measured after 40._ years _thelmal aaino and radiation will be less at.
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' Pilgrim than that p_redicted from the original:tsst.
Assuming'the linear-degradation
' in elongatidii aiid_ accounting for normaTradiaTiofi dose, the lic'ensee has evalui~tW-(
that 41/2 years of. remaining. life is left for the subject cables between elevation 41' and 73'.
Based on the above the staff agrees with the licensee's usessment that continued operation is justified.
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- 10. Okonite pbwer and control cable Okonite insulation, Oko' pre'ne jacket ~
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The licensee has replaced the subject cable above 41' elevation.
For the cables below 41' elevation, the licensee has provided the analysis which indicated that the jacket might be damaged but the insulation still has the remaining qualified 6.2 years at the rated temperature of 90 C.
The licensee has also 0
indicated that the okonite cable at PNPS was qualifie.d without the jacket.
Based on the above and the fact that the drywell is inerted during power operation and the. jacket is used for the purpose of flame retardancy, we agree wit'h.the lice.is'e'es asse'ssmentind find that contiriu' d operat' ion is ju' tified.'
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11.
GE switchboard wire, type SIS The licensee has perfomed the aging'the rated condition the cable'is g analysis ~which. indicated that the qualified life at 1600F is 45.5 years while at 6.1 years.
The.11,censee has also perfor;ned th.e equivalent degradation time t
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the cable has been used 7.nd indicated the degradation time of 1.7 years at 1600F and 1.94 years at 194 F.
Since the cable has been used since 1972, ten 0
years of the life has been used at the rated temperature.
However, since'the cable will not operate at the rated condition and is expected to operate 0
somewhere.in_be. tween 160 F and 1940, we agree with the licensee's assessment" ~~ ~ \\
and find that continued. operation is justified.~710 wever, the staff ~also
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requires't'h'at the. licensee 'should submit the' Hew a~nalysis based oit the temperature
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rise-based on cable use and. demonstrate that continued operation is justified beyond one refueling outag6.'
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Raychem cable splices..model WCSF-N
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,.y The: licensee h.as perfomed an aging analysis and detemined that the material.
. which comprises this equipment is insensitive to themal degradation for the:
. range of temperatures to which it was exposed.
We have reviewed the infomation provided by the licensee and find that continued operation is justified.
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GE electr'ical penetration, cannister type.
The license _e has perfomed an aging analysis and demonstrated that continued
' operation is justified.
The staff agrees with the licensee's assessment except for the cables. The licensee is using the GE SIS type wires. The staff's pos'ition regarding the Based on our evaluation,..
of the licensee's asses.se wires. is covered.in Item 11.
sment, we find that con _tinued operation is justified.
i 14.
Physical ' science electrical penetration The licensee has performed"an aging analysis and determined that this equipment contains no age sensitive materials which would compromise pressure boundary integrity.
In addition, testing.has been performed during this outage:.to.
cstablish the pressure integrity. of this equipment.
Based upon our review of the information provided by the licensee, we find that continued operation is justified.
15.
Bergen Patterson snubbers
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The licensee has performed siiginWn'alifis and based in'~tfirs inily~sfs has T
i replaced al.1 snubbers above 44' elevation.
All snubbers below 44' elevation i
have a remaining life of 6.9 years at 194 F. Based on' our evaluation of the 0
licensee's assessment, we find that continued operation is justified.
l 16.
ITT Hamel-Dahl air operators The licensee has perfomed an aging analysis and oetermined that Buni-N'o-rings' and Buna-N/ nylon diaphragms have an expected life of on1.y 39 days. The licensee'has also stated that these air operators are fail safe and failure of any ncnmetallic part will not impair the safe o'peration of the plant.
The licensee will disassemble.
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. Air regulators will be replaced.
Jased on our evaluation of the licensee's assessment :we find that' continued 6p: ration is justified.
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Hydroline air operat6rs The licensee has perfomed an aging analysis and determined that continued operations is justified.
Based upon our review of the infomation provided by the licensee, wMjfd.dh.at continued operations is justified.
C.
Accident Analyses The effect of high~ initiai 'drywell temperature on desigri basis. loss:of.
coolant' accident (LOCA) analyses was reviewed.
The design basis LOCA results in the most severe drywell pressurization rate.and peak pressure loading... -
Therefdre, it.is bounding for o'ther accidents. The containment pressure / temperature response results for a number of higher initial drywell temperatures was compared with the results obtained from analyses assuming an initial drywell temperature 0
of 135 F (average design drywel.1 temperature).
These analyses indicated that lower peak pressures and lower drywell pressurization rates resulted when higher initial drywell teinperatures were assumed and that the effect on' peak post-LOCA drywell temperatures was negligible.
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These results are expected since higher initial drywell temperatures re: ult in a lower ai.r density and mass than at lower temperatures: Thus, both peak post-LOCA drywell pressure and drywell pressurization result.
Likewise, the
'effect on p(eak temperatures would also be expected to be negligible because of the small relative to post-LOCA heat addition) additional heat content of the drywell atmosphere and structure as a result of high initial drywell temperatures.
Finally, regression analysis results obtained from the Mark I Containment Program 1/4 Scale. Test Program have demonstrated.that torus pool swell loads (both downforce and upforce) will' be lower for a higher initial drywell temperature.
Therefore, we concl.ude that operation with a drywell ambient ' temperature h'igher than the nominal design \\value does not adversely affect accident analyses previously perfomed.-
D.
Technical Specifications The licensee has proposed Technical Specificat. ions which provide LCOs and surveillance requirements for drywell temperatures and for drywell temperat'ure mongtoring instrumentation. These TS provide a drywell temperature limit of 194 F above elevation 40' and 1500F at or below elevation 40'.
These temperatures were developed taking into consideration the long-term effects of ambient temperature on equipment design limits and materials of components required for accident mitigation or plant shutdown.
Upon exceeding the proposed TS temperature limits, an engineering evaluation is required to be perfomed to assess potential damage and render a detemination as to the ability of safety related equipment to perform its intended functions.
0 I'n addition, if the drywell temperature at an.y elevation. exceeds 215 F for more than 30 minutes, the proposed TS requ. ires the plant to be.in a cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
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Finally, limiting conditions for operation and surveillance requirements for drywell temperature monitoring instrumentation have been proposed which provide assurance that the temperature monitoring instrumentation is operable at different elevatior.s throughout the drywell.
We have reviewed the proposed TS and have determined that they limit centainment drywell temperatures to values which will not have an adverse impact on drywell equipment, components, and structures required for. safe. plant operation...;
Consequently, we find the proposed TS changes acceptable.+
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. 4.0 Environmental ' Considerations
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We have determined that the amendment does not involve a change in effluent types or total amounts nor an incr~ ease in power: level and will not result in any significant environmental impact.
Having made this determination, we
, have: further conc 10ded that the amendment involves an action which is insignificant from the standpoint of environmental impact and pursuant to 10 CFR 51.5(d)(4) that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of the amendment. -
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Conclusions
' We have concluded, based on the considerations discussed above, that:
(1) because the amendment does not involve a significant increase in,the -
probability or consequences of accidents previously considered and does not l
2 involve a sig'nificant decrease in a safety margin, the amandment does not-involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed ' anner, and (3) such activities will be conducted ~
m in compliance with the Commission's regulations and the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
i Dated: March 20,1982 e
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