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/ 'o UNITED STATES

8 NUCLEAR REGULATORY COMMISSIONgo

WASHINGTON, D. C. 20555r,; y

%...../SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION

RELATING TO TORUS P0OL TEMPERATURE INDICATION

AND THERMAL M:XINr. MODIFICATIONS

GPU NUCLEAR CORPORATION

JERSEY CENTRAL POWER AND LIGHT COMPANY

OYSTER CREEK NUCLEAR GENERATING STATION

DOCKET NO. 50-219

1.0 INTRODUCTION

31, 1985, and supplemented by letters dated June 16,By letter dated OctoberJuly 22 and August 4, 1986, GPU Nuclear (the licenseel proposed to cancel twomodifications to provide (1) local suppression (torus) pool temperaturemonitoring at the electromatic relief valve quenchers, or discharge headers, inThe licenseethe pool and (2) thermal mixing for pool near the quenchers.considers these modifications are part of the scope of work required by the

13, 1981 Order and DecemberConfirmatory Order, " Modification nf the JanuaryThis Order is related to the Mark I19, 1982.29, 1981 Order", dated' January (LTP) and would require the licensee to completeContainment Lono Term Programthese modifications before the restart from the Cycle 11 Refueling (Cycle 11R)

commenced in April 1986 and is scheduled to end inoutage. This outageOctober 1986.

2.0 BACKGROUND

The primary containment for Oyster Creek is the drywell and the torus.This is discussed in Section 6.2 of the Oyster Creek Updated Final Safety

The function of thisAnalysis Peport (FSAR) dated December 1984containment is to accommodate, with a minimum of leakage, the pressures andtemperatures resulting from the break of any orocess piping in thecontainment including reactor coolant system piping.

In its letter dateo October 31, 1985, the licensee stated that the BWRreport, " EliminationOwner's Group (BWROG) General Electric (GE) NE00-30832of Limit on BWR Suporession Pool Temperature on SRV (Safety Relief Valve)Discharge with Quenchers" dated December 1984, concluded that unstablesteam condensation is not a concern where quencher devices are used on SRV

The licensee stated that quenchers have been installed atdischarge piping. TheOyster Creek and the NEDO-30832 report is applicable to Oyster Creek.above two modifications were for the operators to be able to monitor the localpool temperatures in the vicinity of the quenchers and provide additional themalmixing at the quenchers to prevent the onset of unstable steam condensation at

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the quenchers during SRV discharges to the torus and the resulting dynamic load'

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The NED0-30832and possible damaqe to the SRV discharge piping and torus.report concludes that significant unstable steam condensation and dynamic loadswill not occur with quenchers.

The staff has not started its detailed review of the NED0-3083? report.

3.0 EVALUATION

The licensee reouested to cancel two mndifications for suppression poolthermal mixino based on BWROG's NED0-30832.

20, 1986, Progress Review MeetingThe licensee explained in the Februarythat the two modifications are (1) adding(summary dated March 14,1986)temperature monitoring in the vicinity of the two Electromatic ReliefValves (EMRV) discharge headers in the torus and (P.) rercuting a containmentspray dynamic test return line. They are part of the torus attached pipingmodifications in the licensee's letter dated June 29, 1981. The purpose ofthe modifications is the following:

To give the control room operators indications that the(1) temperature of the water in the vicinity of the EMRV headers isreaching the point where unstable condensation would occur andresult in dynamic loads on the suppression pool shell duringblowdown from a stuck coen EMRV. This would read out in thecontrol room.

(2) The operators would know, by the local pool water temperature,that they had a stuck open EMRV. In Germany, a stuck open EMRVwith a straight open header resulted in unstable condensation of

Tnere wassteam 'n the pool and localized dynamic loading.The work by Generalrocking of the torus and local damage.showed that unstable steam condensation isElectric in NE00-3083?not a concern when quencher devices are used on EMRV dischargepipina as exists at Oyster Creek.

The test line is used for testing the operability of Containment(3) Presently it is routed into a torus /drywell vacuum breakerSpray, The rerouting was toand drains into the torus suppression pool.allow means to cause some recirculation in the pool to aid inthermal mixing in the vicinity of the EPRV discharoe headers andThere was no safety problem withlower local pool temperatures. The newthe test line in its present design and location.design would be used, in coniunction with the temperaturemonitoring and knowledge with the operators that they were at thetemperature for the onset of unstable condensation, to (1) causebetter thermal mixing in the vicinity of the headers and (?)prevent unstable condensation conditions.

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The temperature monitoring in itself would not prevent any unstableconditions and there are other safety grade and redundant indications to

These indications are in th TS andidentify when an EMRV is stuck open.There is clso torus bulk water temperatureread out in the control room. The operators have Emergency Operatinoindication in the control room. This was verified andProcedures (E0P) addressing a stuck open EMRV. 21, 1986, in a tour of thediscussed briefly with the operators on FebruaryThe location for and size of thecontrol room by the NRC Pro,iect Manager.rerouted test line does not indicate it would be effective in causing toruspool circulation in the vicinity of the headers.

These modifications were to prevent unstable steam condensation from EMRVdischarges into the pool by (1) temperature monitoring to see onset oftemperatures which will cause unstable steam condensation at the header and(2) discharges from the rerouted test line to causing circulation of theAs shown in Figure T-1 inpool and reduced temperatures at the header.NEDO-30837, a straight pipe discharge into the pool will cause large dynamicloads which resonate or peak with respect to the pool water tercerature.The Figure 3-2 in NE00-3083F shows that for discharoes through quenchers,which is the situation at Oyster Creek, the dynamic loads are significantlyreduced.

The above modifications are not part of the licensee's modification tomonitor the torus bulk water temperature in accordance with NUREG-0661.The latter modification for torus bulk water temperature is part of thestaff's Long-tern Mark 1 Containment Review and Confirmatory Order dated

The licensee reauested in its letter dated July 26, 1985, toJanuary 19, 1982.defer this latter modification (Item 6 of its letter) from the Cycle 11RThis decision will be the sub.iect of a separateoutace to Cycle 12P outaoe.letter to the licensee on its July 26, 1985, request.

4.0 SUMMARY

Based on the above, the staff concludes that the two modifications presentedabove are of insufficient safety significance to warrant having the licensee deIn fact, the steff has reviewed itethe modifications in the Cycle 11R outage.Safety Evaluation (SE), " Mark I Containment long Term Program - Pool DynamicLoads" dated January 13, 1984 and the January 19, 1982 Confirmatory Orderand concludes that the modifications are not part of the Mark I Containmentmodifications required to be completed in the Cycle 11R outage.

The Mark I Containnent Confirmatory Order requires only plant modificationsneeded to comply with the Acceptance Criteria in Appendix A of NUREG-0661,The applicableMark I Containment long-term Program, dated July 1980.Acceptance Criteria for these torus modifications is the local suppressionpool temperature limit for safety relief valve discharge loads in SectionBecaure for Oyster Creek the maximum local2.13.8, page A 41, of Appendix A.to bulk suppression pool temperature is 43*F (i.e., the Monticello test withnutthe residual heat removal system on page 125 of NUREG-0661) and the maximumallowed bulk temperature is 95*F (i.e., Technical Specification 3.5 A.1.7for reactor operation as explained in the licensee's letter dated August 4,1986), the maximum local temperature is less than the 200"F Acceptance Criteria

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in Appendix A, page A 41. It is also less than the 160 F criteria in the Basesof Section 3.5, Containment, of the Technical Specifications, for relief valveoperation with sonic conditions at the discharge exit to avoid the regime ofThe staff, therefore, concludespotentially high suppression chamber loading.that these torus modifications are not needed, and were not needed, to meet theAcceptance Criteria of NUREG-0661 and, therefore, are not part of the modifica-tions reauired by Confirmatory Order dated January 19, 1982.

In the meeting of April 10, 1986, the staff presented a Request for AdditionalThe RAI had ouestions onInformation (RAI) to the licensee on this sub,iect.

(1) the applicability of the request to cancel these torus modifications tothe Acceptance Criteria in NUREG-0661, Mark 1 Containment Long-Term Program,dated July 1980 and (2) the relationship between the initial suopression pooltemperature for the design bases Loss-of-Coolant Accident (LOCA) analysisand the pool temperature limits in the Oyster Creek Technical Specifications

The RAI were sent to the licensee in the staff's letter of May 5,(TSl.1986.

The licensee responded to the staff's PAI in its letters dated June 16,In these responses, the licensee statedJuly 22 and August 4, 1986.that without thest tool modifications the local pool temperature will notexceed the limits dictated by the Acceptance Criteria of NUREG-0661 duringthe most severe relief valve transients of interest and that the initialsuppression pool temperature is consistent with the temperature limits inthe TS and the net positive suction head exists at this temperature for thecore spray system pump which draws suction on the suppression pool during

The resolution of the staff's concerns on the initialthe LOCA.suppression cool temperature was addressed in the staff's letter to thelicensee dated

5.0 CONCLUSION

Based on the above, the staff concludes that these modifications are notrequired as part of the Mark I Long-term Program Confirmatory Order toTherefore, theseaddress safety relief valve discharge loads on the torus.torus modifications are not required for the safe operation of Oyster Creekand the staff concludes that the licensee does not have to do theThe staff is, therefore, in agreement with the licensee onmodifications.cancelling its comitment to install these modifications.

6.0 REFERENCES

Letter from P.R. Fiedler (GPUN) to John A. Zwolinski (NRC) with1.attachment, dated October 31, 1985,

Letter froa Dennis M. Crutchfield (NRC) to P.B. Fiedler (GPUN) with2.attachment, dated January 13, 1984.

Letter from Dennis M. Crutchfield to I. R. Finfrock, Jr. (GPUN) with3.attachment, dated January 19, 1982.

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General Electric, NED0-30832, Elimination of limit on PWR SuppressionA.Pool Temperature on SRV Discharae with Quenchers," dated December 1984.

5. February 20, 1986, Proaress Review Meetino on Licensina Actions, summarydated March la, 1986.

6. Letter from J. Zwolinski (NRC) to P.R. Fiedler (GPUN), Meetino ofApril 10, 1986, on Requested Cancellation of Nitrocen Purce/ Vent System,May 5, 1986.

7. Letter from R.F. Wilson (GPUN) to John A. Zwolinski (NRC), CombustibleGas Control and Supnression Pool Te-oerature Linits, dated June 16, 1986

8. Letter frem R.F. Wilson (GPUN) to John A. Zwolinski (NRC), Peouest forAdditional Information Concernino Safety Relief Valve Discharges to theSuppression Pool, dated July 22, 1986.

9. Letter from R.i. Wilson (GPUNI to John A. Zwolinski (NRC), Core SprayNPSH Calculations, dated August 4, 1986.

Principal Contributor: J. Donohew

Dated: October 1, 1986.

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