ML20236H190
| ML20236H190 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 07/23/1987 |
| From: | Bailey J WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | Martin R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| Shared Package | |
| ML20236H179 | List: |
| References | |
| ET-87-0244, ET-87-244, NUDOCS 8708050093 | |
| Download: ML20236H190 (15) | |
Text
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r W$LF ll REEK NUCLEAR OPERATING CORPORATION
$"d.D Enen ms eu ww s.w July 23, 1987 Mr. R.D. Martin, Regional Administrator U.S. Nuclear Regulatory Commission Region IV i
611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 Letter: ET 87-0244 Re Docket No. 50-482 Ref:
Memorandum EGM 85-OSB dated 02/27/87 from HRDenton and JTaylor, NRC to NRC Regional Administrators Subj Enforcement Discretion Regarding Technical Specification 3.0.4 l
Gentlemen:
The purpose of this letter is to request that enforcement discretion be utilized to grant temporary relief' from the requirements of Technical l
Specification 3.0.4 in accordance with the Reference. Enforcement discretion would allow Wolf Creek Generating Station (WO38) to pronptly resume power operation.
The proposed enforcement discretien would allow tenporary relief from Technical Specification 3.0.4 which - requires in part that " Entry into an OPERATIONAL MODE or other specified condition shall not be made unless the conditions for the Limiting condition for Operation are met without reliance on the provisions contained in the ACTION Requirement." Specifically, the requested enforcement discretion would allow WO::S to complete the required OPEPATICt@L MCOE changes necessary to resume POhl'R OPERATICN, while relying on the provisions of Action a.,
of Technical Specification 3.6.2.3.
Technical Specification 3.6.2.3, Containment Cooling System requires that "Two independent groups of containment cooling fans shall be OPERABLE with two fan systems in each group."
AcrION a.
al days provided one group of containmentlows continued power operation for seven systems are OPERABLE.
cooling fans and both containment spray Attachment I to this letter provides a discussion of the circumstances and events which resulted in this request for enforcement discretion. Attac1 mint II provides a detailed safety evaluation of the proposed enforcement discretion.
Although this safety evaluation has been coupleted, the calculations and conclusions of this evaluation are currently being verified in accordance with existing procedures Confirmation of the safety evaluation conclusions will be transmitted to you upon completion of this verification.
8708050093 e7073o PDR ADOCK 05000482 P
PDR Ro Som 411/ Burengeon, KS 66Me / Phone:(316)364 sh31 An Eeuelopportrwty bpeoyer W4CVET
e I
ETr 87-0244 July 23, 1987 Page 2
Based on the disuussion presented in Attachment I and evaluation discretion for this situation would not increase the p the consequences of
-or an accident or m1 function occurrence safety previously evaluated in the of equiprent important to possibility for an accident or safety ~ analysis report;.
or create a malfunction of evaluated previously in the safety analysis different type than any a
safety as defined in the basis for report; proposed temporary relief from theany technical specification.or red the Therefore, adversely affect or endanger the health or safety of the gene requirements of T.S.
3.0.4 would not involve a significant safety hazard.
If you have any questions O.L.
Maynard of my staff. concerning this matter, please contact me or Mr.
Very truly yours, John A. Bailey Vice-President I
Engineering and Technica Services Attachments:
I - Background II
- Technical Evaluation cc P0'Connor (2)
R7ohnson 4
JCumins m
-_-____.______________________u_________..m_m
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t Attactrnent I to CT 87-0244 June 23, 1987 Page 1 of 2 1RCMROUND INMR% TION nnmtymtm On July 20, 1987 at 1149 CDP with the Unit operating at approximately 100 percent power, doclared inoperable and de energized.one of two "B" train containment Cooling Fans tripped and was Action a of Technical specification (T.S.)
3.6.2.3, Containment Cooling System, eas entered due to the inoperable Containment Oooling Fan.
inspection of the inoperable Containment Cooling Pan revealed that one of theSubs sixteen variable pitch fan blades had failed damaging several other fan blades.
Technical Specification 3.6.2.3 requires that "Two independent groups of I
containment cooling fans shall be OPERABLE with two fan systems to each j
group." ACTION a.
of this Technical Specification a.llows continued power operation for seven days provided one group of containment cooling fans and l
both containment spray systems are operable, j
Wolf Creek Generating Station (WCGS) experienced a Reactor Trip at 2303 CD I
July 20, 1987. The Reactor trip appears to have resulted from a power / loa 1
imbalance caused by a fault in one of the WCGS switchyard transformers.
Reactor Trip was in no The way caused or affected by the inoperable containment Cooling Fan.
Trip since T.S.However, WCGS could not resume power operation after the Reactor
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T.S. action statements.3.0.4 prohibited any operational mode change not required j Technical Specification 3.0.4 requires in part that,
" Entry into an OPERATIO!EL ?0DE or other specified condition shall not be made unless the conditions for the Limiting Condition for Operation are met without reliance on the provisions contained in the ACTION Require m ts." Since the unit i
rmained in T.S.
of the plant even though T.S.3.6.2.3 AcrION a., T.S. 3.0.4 effectively prohibited star 3.6.2.3 ACTION a., would have allowed continued mwer operetion for over six days before i
required.
further ccrnpensatory measures were Based on the above circumstances, WCBS deemed it appropriate to reque enforcement discretion allowing temporary relief from the requirertent of T.S.
3.0.4 permitting WOGS to complete the required OPEPATI0faL IDDE changes necessary to resume power operation, while relying on the arovisions of ACTION a.
of T.S.
3.6.2.3 Enforcement discretion would in tais case prevent the unnecessary delay in a Reactor Startup. Repairs to the inoperable Containment Cooling Fan will be completed in accordance with the requirements of T.S.
3.6.2.3.
i Attachment I to Cr 87-0244 i
June 23, 1987 Page 1 of 2 l
MGMxND INFOR% TION Ih7ITODUCPTON On July 20, 1987 at 1149 CDT with the Unit operating at approximately 100 percent power, declared inoperable and de-energized.one of two "B" train containment Cooling Fans tripped and was Action
- a. of Technical Specification (T.S.)
3.6.2.3, Containment Cooling System, was entered due to the inoperable containment Oooling Fan.
inspection of the inoperable Containment Cooling Fan revealed that one of theSubs sixteen variable pitch fan blades had failed damaging several other fan blades.
Technical Specification 3.6.2.3 requires that "Two independent groupo of containment cooling fans shall be OPERABLE with two fan systems to each group." ACTION a.
of this Technical Specification allows continued power operation for seven days provided one grou both containment spray systems' are operable.p of containment cooling fans and Wolf Creek Generating Station (WCGS) experienced a Reactor Trip at 2303 C July 20, 1987. The Reactor Trip appears to have resulted from a power / load imbalance caused by a fault in Trip was in no way caused or affectedone of the WCGS switchyard transforme j
Reactor i
by the inoperable Containment Cooling Fan.
Trip since T.S.However, WCGS could not resume power operation after the Reactor T.S. action statements.3.0.4 prohibited any operational mode change not regai"ad Technical Specification 3.0.4 requires in part that,
" Entry into an OPERATIONAL PODE or other specified condition shall not be made unless the conditions for the Limiting Condition for Operation are met without reliance on the provisions contained in the ACTION rensined in T.S.
Requirements." Since the unit cf the plant even though T.S.3.6.2.3 AC1' ION a., T.S. 3.0.4 effectively prohibited s 3.6.2.3 ACTION a., would have allowed continued power operation for over six days before requirod.
further compensatory measures were Based on the above circumstances, WO35 deemod it appropriate to requ enforcement discretion allowing temporary relief from the requirement of T.S.
3.0.4 permitting WOGS to ecmplete the required OPERATIONAL LODE changes necescary to resume power operation, while relying on the arovisions of ACTION a.
of T.S.
3.6.2.3.
Enforcement discretion Vould in this case prevent the i
unnecessary delay in a Reactor Startup. Repairs to the inoperable Containnwnt i 030 ling Fan will be completed in accordance with the requirements of T.S.
3.6.2.3.
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Attachment I to Er 87-0244 June 23, 1987 Page
- 2 of 2 1
I PTNDTNC9 The Containment Cooling System includes two inde Cooling Fans with two fan systems in each group. pendent groups of Containment The Containment Cooling Fan i
Blado Assembly consists of sixteen variable pitch blades bolted through a hub.
The damaged fan blade assembly was removed from the motor, disassembled and inspected. Inspection - confimed that one fan blade had sheared along its 1
threaded portion. Thirteen of the i
apparently inflicted by the failed blade. sixteen fan blades exhibited some damage The fan blades and the hub were non-destructively examined and no indications were identified.
During examination of the fan motor, it was identified that the motor shaft had excessive runout which indicated a possible bearing failure.
This fan motor is being replaced with a new assembly. The damaged fan blades are also being replaced.
- However, are not immediately available.since the blades must be remanufactured, replacements The inoperable Containment Cooling Fan should be restored by July 26, 1987.
allowed by T.S. 3.6.2.3.
This is within the seven day action statement CONCID9fots The exact nature of the biade failure is currently under evaluation, however_
the three remaining containment cooling Fans were inspected to verify that the fan blades were firmly fastened, at the correct pitch, and that there was no excessive motor vibration. This information indicates that the fan blade failure was an isolated event not indicative 'of a generic design or
- manufacturing error that would result in the simultaneous failure of the other Containment Cooling Fans.
.4 4
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Attachment II to ET 87-0244 Page 1 of 11 i
July 23, 1987 I
nasamenr, amamme I.
DESCRIP1'EM & SM 2e containment oooling systen, operating in conjunction with the containment heating, ventilating, and air-conditioning system is designed to limit the a#ent contalment air _ temperature during nomal plant
-)
operation to 120"F with three of the four contaiment cooler fans R
l operating. During normal t operations, the hAvv mixing fans are I
designed to provide suffic ent air flow through the steam generator I
ocupartments so that a suitable envim..ut for the equipnent in the steam generator ccupartment can be maintained.
Se containment cooling systen provides cooling by recirculation of the containment air across air-toeter heat enchangers. % e bulk of this cooled air is supplied to the lower regions of the steam generator ogqpartments.. Se remaining air is sciiM to the instrument tunnel and at each level (operating floor and below) of the containment outside the i
secondary shield wall. S e air ied to each steam generator ocmpartment is drawn upwards the caripartments by the hAww.
mixing fans and discharged into the upper elevations of the containment.
Se containment cooler fans are located vertically in the bottaa of the i
cooler housing.
Fans are var rial fans with M r' ring normal plant 71 sotors. Se fans I
and motors are dosi for high-speed operation du operations and for opocetion under post-Kass of Coolant W%t (IOCA) conditions.
II. 'M2EE3h EFE3FIDEE16 In consideration of single failures with only three omtainment cooling fans operating, either one or two containment coolin operation depending on the location of the failure. g fans would remain in For
, if a loss of one esamtial service water train were to coeur, the condition would be one contalment cooler fan remaining in opezation.
Should this occur and both oantainment spray systene runnin ~hle, Action statement b.' of Technical specification 3.6.2.3 would En entered.
Action statament b. requires restoration of two containment cooling fans to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in Hot Standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in cold shutdown within.the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
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Attachment II to ET 87-0244 July 23, 1987 Page 2 of 11
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As identified la the bases for Technical Specification 3.6.2.3 the-containment ecoling syntam and contaimant spray system are refundant to each other with ard to providing post socident cooling of the containment atnos the basis for the 7 day out-of-service tims of Technical Specific 3.6.2.3 was established.
The action statement associated with action statement a. reflects a defense-in-depth approadt diidi is conservative relative to Engineered Safety Feature (EEF) performance requirements.-
Technical Sp/or conpanents be y=hle and allecifiestion 3.0.4 re systerns and parmestere as specified in the limiting conditions for operation be met without regard for alicumble dwiations and out-of-service prorisiens in the action statements, prior to entry into an operational mode.
intent of this provision is to ensure that the facility operation is notA initiated with either required equipment or systems i& =hle or other specified limits being a mmadad. As pewiously dh==ad Technical Specification 3.6.2.3 action statement a. was antered due,to the looparability of containment cooler fan 83015.
Due to the suisting redundancy between the contaissnant cooling systen and containment s systens as previously described, return to power should not be delayed solely by tie absenos of 8301B as adequate BBF the ocnfines of Technical Specification 3.6.2.3,Th"ities exist within the intant of the referenced Technical Specification since, with no9da is cons containmmt fans <==31e, 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for restoration is a11 cued, therefore the intent of 3.0 4 is satisfied.
III. EERMIM
'Jhe design of the containment cooling System iisors=tes two redundant trains containing tuo contairunnst cooler fans one containment cooler fan were out of service mLe%per tamin.
If t with the worst case single failure of two additional cooler fans due to diesel failurv or loss of assential service Mater (85W),. only one containment design basis accident.ocolar fan may be available for contairmant heat re On this basis, the contairunant pressure-tmperature analysis presented in Updated Safety Analysis Report (IEAR) Section 6.2.1 was reenalysed assundng caly one cooler fan in operation to detann baramture and pressure. ine the impact en containment post Wd-st This remnalysis was perfonned using the same ocmputer code and design iryats as was used in the analysis presented in USAR Section 6.2.1 except one was pcotulated available in lieu, of two (2).(1) containment cooler fan i-t 5
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Attachment II to ET 87-0244 Pacje 3 of 11 July 23, 1967 Based en a zwiew of the 11X:A and Main Steam Line Break pressure-tanparature analysis cases previously analyzed, it was detamined t)at the worst case ICCA (Case 1 of USAR Table 6.2.1 the two worst case MSIA and need only to be reanalyze (Cases 6 and 12 of USAR Table 6.2 d.
% ese cases represent the peak containment tenparature and pressure cases for both IKA and MSta.
j We results of this remnalysis for IKA and M5tA demonstrated that the peak tarporatures increased by less than 1/2% over the values reported in USAR mables 6.2.1-8 eM 6.2.1-58.
In addition, the peak pressure for the ItcA case increased less than 1
0.8% over the values peesented in USAR Table 6.2.1-8.
However, the peak pressure for the wormt case MSrA increased aW'aately 7.2 psi. Sia peak pressure occurs at 1800 seconds, winn blowdown is -
terminated fra the faulted steen generator. In addition, the pressure and tenparature profiles for the long tem, after the peaks are reached, are slightly above those presented in the figures of UshR Section 6.2.1 for the worst case breaks.
Preliminary graphs of the pressure and tangerature results of this rannalysis are attached for information (Pages 6 through 11 of this attachnent)-
It should be recognised that the containment pressure-tauperature 1
angysisconsidersdesignfoulingforthecontainmentaircoolersand
)
957 cooling mter supplied by the Essential Service Mater Syntast. _
mese are both car.mervative assumptions whan considering that the centainmmt omlars have only cTarated a few years and lahn tanparatures during the sunner m:nths have averaged less than 8S 7, 0
%e nw tangerature and pressure profiles described above were then utilised in a review of the ewisonmental gnalification reports for i
safety-related pment insido contaiment. 'Ihm results of the review envixermental qualification as previously establiaiad in i
0588 submittal for e lf Creek Generating Statien.
provides a summary of the significant aspects of the zwiews%e following Sc conparison of the new pressure profiles with the existing environmental qualification pressure profiles reveal that surgin would continue to exist for either postulated accident (IcCA or MSIA).
Se new margin es+=Wahed by the current enviremental qualification report is at least 10 psi when compared with the_new peessure profiles,
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1 Attacha nt II to ET 87-0244 Fage 4 of 11 July 23, 1987 k
In addition, the ocuparison of the new taperature profiles with the existing environmental qualification t e am ture profiles revealed that a ite [MstA + IMA t P ture profile was ificattan whleh env) elopes the new tagerature utilized during j
l profiles for all two (2 easee.
supplied in accordance with)four (4) design specificatims wereIn ;
i qualified to only the Itch taperature profile..It was detemined that the existing qualification profiles env=1W the new-taperature profile developed for IMA.
In the second ceae, equipment supplied in accordance with eleven (11) design specifications were qualified to a surface ta perature profile that was generated us the Mara taperature profile to provide qualification ts. 1he qualification reports indicate the equignant was he d at the
' n excess of the time arv 4< tant taiparature for a duration i
to satisfy tw surface tangerature profiles. In addition, the qualification report revealed that the limiting envirG...tal condition is peak taperature. 1herefore, because the new t
=9nure profiles did not appreciably affect the
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peak taperature acftieved during NBra, the existing env.renmental qualification for this case is not s..y.wnised.
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The results of the reanalysis was also reviewed against the current t
accident analyses as described in Chapter 1$ of the USAR and detemined that the higher resultant containment pressure-temperature profiles i
caused by the MM heat removal rete will have no adverse inpact on the Chapter 15 accident anal utilised in the sooident The mass and energy release data yees were developed by using a exmservative ocmstant contalment backpressure to adhieve a anwbme di rate. The accident analyses do not take credit for decreas discharge rate due to the increase of ocatainnent backpressure under nonw:hoking conditions.
Additionally, the consequences of an increase in containment pressure due to the new pressure profiles for a MRA were evaluated.
The increase in containment pressure for an Meta of 7.2 psi places this pressure above the test pressure at dtids the(to 55.3 peig)
Integrated i
Isak Aate Test (m) was perfoened.
She M was perfomeed at 48.1 peig as 6' anted in the Final Report for the Primary containment Integrated Imak Rate Test.
of the USAR Sectica 15.1.5) documents that for radiological 1hs consequences, the bounding MEra accident analysed is an MBIA outside ocmtainment.
Sherefore, the increase in contalment pressure frca en MSIA within ocatainment has no offact cm the bounding MSIA radiological analysis. Note design pressure for the contaiment boundary is 60 psig.
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Attach:nent II to ET 8'l-0:44 Page 5 of 11 July 23, 1987 V.
REPAIR & Dmgenn ran umr-; pagRt NmW F-i-1 and 2)
Repair efforts are currently underway to restore.the damaged fan to operable status. It is ant.cipated that the remaining work to be performed in Modes 1 and 2 is the replacement of the h1mdfn assembly and the subsequent reassembly of the fan housing. g and hub i
.1his work is to be perfomed within the containment in the idiete area of the.
fan.
Use of the polar crane is required at the fan for this effort.
ne use of the polar crane to facilitate rework of tta containment cooler was evaluated.
Worst case postulated drops ware' analyzed and found to have no adverse Japact en plant shutdem equipment Load paths were defined and plant node restrioticms.were esblished j
for described M. offort.
VI.
333 3 As described in the above W Mg sections, the effects of operating Wolf Creek Generating C&ycation with three cooler fans in both normal and
- 3) containment evaluated and found accootable.postwocident conditions (have
- h e evaluations considered the worst case single failure which resultad in operation of one (1) containment cooler fan operation during post eocident conditions.
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Serefore, the operation of Holf Creek Generating Station in Modes 1 and 2 with three l
confines of Technica(3) <T==Me contaiment cooler fans in the adversely affect the health and safety of the public.l Specificat i
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