ML17156A124

Application for Proposed Amends 66 & 19 to Licenses NPF-14 & NPF-22,respectively,changing Tech Specs to Support Operation W/One Recirculation Loop Out of Svc

ML17156A124
Person / Time
Site:	Susquehanna
Issue date:	04/11/1985
From:	Curtis N PENNSYLVANIA POWER & LIGHT CO.
To:
Shared Package
ML17156A125	List: ML17156A124 ML17156A126 ML18040A775
References
NUDOCS 8504180546
Download: ML17156A124 (14)

Text

BEFORE THE UNITED STATES NUCLEAR'REGULATORY COMMISSION In the Matter of PENNSYLVANIA POWER & Docket No. 50-387 LIGHT COMPANY PROPOSED AMENDMENT NO. 66 FACILITY OPERATING LICENSE NO. NPF-14 SUSQUEHANNA STEAM ELECTRIC STATION UNIT NO. 1 Licensee, Pennsylvania Power & Light Company, hereby files proposed Amendment No. 66 to its Facility Operating License No. NPF-14 dated July 17, 1982.

This amendment contains a revision to the Susquehanna SES Unit 1 Technical Specifications.

PENNSYLVANIA POWER & LIGHT COMPANY BY:

N. W. Curtis Vice President Engineering &

Construction Nuclear

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C 9 BEFORE THE UNITED STATES NUCLEAR REGULATORY COMMISSION In the Matter of PENNSYLVANIA POWER 6 Docket No. 50-388 LIGHT COMPANY PROPOSED AMENDMENT NO. 19 FACILITY OPERATING LICENSE NO. NPF-22 SUSQUEHANNA STEAM ELECTRIC STATION UNIT NO. 2 N

Licensee, Pennsylvania Power 6 Light Company, hereby files" proposed Amendment No. 19 to its Facility Operating License No. NPF-22 dated March 23, 1984.

This amendment .contains a revision to the Susquehanna SES Unit 2 Technical Specifications.,'

PENNSYLVANIA POWER 6 LIGHT COMPANY BY:

N. W. Curtis Vice President - Engineering 6 Construction Nuclear c bed before me 1985.

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SUSQUEHANNA SES UNIT 1&2 SINGLE LOOP OPERATION SALARY REPORT CONTENTS

1.0 INTRODUCTION

2.0

SUMMARY

OF SLO REVIEW 3.0 MCPR SAFETY LIMIT 4.0 ANTICIPATED OPERATIONAL OCCURRENCE 5.0 POSTULATED ACCIDENTS 6.0 JET PUMP GAPS 7.0 RELOAD ANALYSIS

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1.0 INTRODUCTION

Single loop operation (SLO) is beneficial when maintenance on a recirculation pump or another component renders one loop inoperable.

Anticipated Operational Occurrence (AOO) and Postulated Accidents associated with power operation were reviewed for the single-loop case with only one pump in operation. The results of the review demonstrate that SSES Unit 1 and 2 can operate safely in SLO with modified Technical Specifications.

This report summarizes the analysis performed on SSES Unit 1 and 2 to operate in SLO. General Electric Company (GE) performed the SLO analysis for the first cycle of SSES Unit 1 and 2. Exxon Nuclear Company (ENC) performed the SLO analysis for SSES Unit 1, cycle 2 with ENC fuel.

2.0

SUMMARY

OF SLO REVIEW A review of the limiting AOOs was performed by GE to demonstrate adequate margin to the MCPR Safety Limit. A review of the values used in the statistical analysis of the determination of the fuel cladding safety limit was performed. Increased uncertainties for the total core flow and TIP readings resulted in a 0.01 increase in the MCPR safety limit.

Although the MCPR increased by 0.01, the analysis of the AOOs demonstrated there is enough margin not to increase the MCPR operating limit or" the flow dependent MCPR limit. (See Section 4.0 below)

A review of the LOCA event was performed both by GE and ENC. The analysis of the limiting recirculating pump discharge pipe break, while in SLO, results in a longer (+11 sec) peak node uncovered time. To maintain the same peak clad temperature as in'wo loop operation, the analysis shows the Maximum Average Planar Linear Heat Generation Rate (MAPLHGR) needs to be reduced by a factor of 0.81. The containment response for a DBA recirculation line break in SLO is bounded by the rated power two-loop operation analysis presented in the FSAR. (See Section 5.0 below)

Thermal-hydraulic stability was evaluated for its adequacy with respect to General Design Criteria 12 (10CFR50, Appendix A). It is shown that SLO satisfies this stability criterion. In addition, SSES Technical Specifications have implemented surveillance requirements for detecting and suppressing power oscillations.

The fuel thermal and mechanical duty for transients occurring during SLO was determined to be bounded by the fuel design bases. Based on vessel internal vibration, the operating loop pump is limited to 90% of rated speed. GE also performed a vibration analysis and a review of test data taken during SLO on jet pumps with and without restrainer set screw gaps.

The results show that on Unit 1, with postulated get pump gaps, the recirculation pumps can operate up to 80% of rated speed in SLO. (See Section 6.0 below)

ENC performed a review of SLO for SSES Unit 1. The ENC review centered on the compatibility between ENC Sx8 and GE 8x8 fuel. The review of the two-loop analyses shows comparable results for operational transients between ENC 8x8 and GE 8x8 and somewhat higher MAPLHGR limits with ENC methodology. Consequently, the ENC review shows the GE SLO analysis is conservative for ENC fuel. (See Section 7.0 below)

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3.0 MCPR SAFETY LIMIT A review of the uncertainties used in the statistical analysis to determine the MCPR safety limit was performed. Except for the total core flow and TIP reading, the uncertainties are not dependent on the mode of recirculation operation. Uncertainties used in the two-loop mode of operation are documented in the FSAR,(Section 4.4, Table 4.4-6). For SLO the total core flow measurement uncertainty increased to 6% (compared to 2.5% for two-loop). The TIP uncertainty increased to 6.8% (compared to 6.3% for two-loop). The net effect of these two revised uncertainties is an incremental increase in the MCPR safety limit of 0.01 during SLO (from 1.06 to 1.07).

The increase in total core flow uncertainty is due to the additional uncertainty in measuring the back flow through the inactive jet pumps.

The total core flow is equal to the active loop flow less the back flow through the inactive jet pumps. The core flow is automatically adjusted for back flow by the installed reverse flow summers. A conservative analysis resulted in an additional uncertainty of 2.6% (for a total of 5.1% and for conservatism a 6.0% will be used).

The increase.,in TIP reading uncertainty is due to the TIP noise in SLO.

GE performed a review of the random TIP noise measurement uncertainty analysis which was conducted at a BWR in SLO. The results of adding the new SLO random TIP noise measurement uncertainty component into the process computer TIP reading is an additional uncertainty of 0.5% (for a total of 6.8%).

4.0 ANTICIPATED OPERATIONAL OCCURRENCES A review of all the Anticipated Operational Occurrences (AOOs) associated with power operation was performed. The results of the review of the pressurization, flow increase, flow decrease, and cold water events show the FSAR analysis at rated power and flow bound the consequences of SLO.

Operating in SLO results in a lower initial maximum core power.

Therefore, the consequences of an event are less severe. For SLO, the two most limiting transients, core flow increase and the pressurization events were analyzed (feedwater flow controller failure and generator load reject with bypass failure respectively). Because of back flow through the inactive jet pumps, the APRM rod block and scram, and RBM equations are modified for SLO.

A feedwater controller failure initiating at 75.6% rate power and 60.3%

rated core flow results in a transient delta CPR of 0.17 (compared to 0.21 for rated power). A generator load reject with bypass failure initiated at the same initial conditions resulted in a transient delta CPR of 0.18 (compared to 0.25 for rated power). Since the initial operating limit in SLO is equal to or greater than at rated power and the transient delta CPR is less in SLO, there is more margin to the safety limit in SLO than at rated power.

A parametric analysis of the generator load reject with bypass failure shows that operating at an initial lower power will result in a lower peak steam dome pressure. Consequently, the rated power FSAR analysis bounds SLO.

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The rod withdrawal error analysis takes credit for the rod block and scram trip systems. Since SLO'esults in back flow through the 10 inactive jet pumps, the equation of the total drive flow needs to be modified for the back flow. The new equation corrects for the difference between the two-loop and single-loop effective drive flow at the same core flow. This is accomplished by substracting 7% rated flow from the active pump drive flow. The rod block and scram trip equations will then have the correct/true core flow for calculating the setpoint.

Consequently, t'e margin to the MCPR safety limit is preserved and the rod withdrawal error analysis at rated power presented in the FSAR bounds SLO.

5.0 POSTULATED ACCIDENTS An analysis of the rod drop event was not performed as the worst case event is at zero power. Consequently, the two-loop FSAR analysis bounds SLO. An analysis of the Loss of Coolant Accident was performed to determine if the two-loop analysis is conservative for SLO. GE analyzed a full spectrum of breaks for SSES using generic SLO methodology. The results show the 66% DBA discharge break is the most limiting large break LOCA (compared to 68% DBA for two-loop). The results of the small brpak (51.0 ft ), the recirculation suction break, and the 100% DBA (1.9 ft )

LOCAs show the 66% DBA discharge break is more limiting.

The LOCA analysis was performed assuming the worst single failure is an inoperable LPCI injection valve. The worst single failure is the same for two loop (FSAR Section 6.3.3.7.4) or single loop operation. The SAFE/REFLOOD codes were used and this resulted in a 66% DBA recirculation pump discharge break being the most limiting LOCA. The maximum peak node uncovered time is 138 seconds (compared to 127 seconds for two-loop).

Based on the generic alternate procedure described in Reference 3, a two-loop reflood time of 195.64 seconds and a two-loop boiling transition time of 20.8 seconds, the analysis requires a MAPLHGR reduction factor of 0.81 on the two-loop MAPLHGRs. The computer code CHASTE was also run to verify the MAPLHGR reduction factor. 0 The result of the analysis 0

show the maximum peak clad temperature is 1866 F compared to 1874 F for the most limiting two-loop FSAR analysis (FSAR Table 6.3-3). Consequently, the two-loop margin to the licensing limit (2200 F) is maintained in SLO.

6.0 JET PUMP GAPS The jet pump beam hold down bolts on Unit 162 were retensioned to reduce the load on the inlet risers. During the Unit 2 jet pump inspection after the cavitation test, gaps on the jet pump restrainer bracket were discovered. The gaps are believed to have occurred during the retensioning of the hold down bolts. The bracket is between the mixing assembly and the diffuser, and is attached to the inlet riser. A maximum of a 20 mil gap was measured between the restrainer set screws and the inlet mixer. The Unit 2 jet pump restrainer was retensioned to eliminate the set screw gaps. Since Unit 1 was operating, a measurement of the set screw gaps could not be performed. Consequently, a maximum gap of 30 mils was conservatively assumed to exist on Unit 1. Measurements taken during the Unit 1 first refueling outage have validated this assumption, as a maximum gap of 26 mils was found.

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GE performed a jet pump vibration analysis assuming SLO with a 30 mil set screw restrainer gap. Vibrational loads and stresses during SLO, transients, and unbalanced flows were analyzed. The analysis also included data from several operating BWRs.

The vibrational frequency and strain at various pump speeds in SLO was compared to rated power and flow. The results at 80% speed with a maximum of 30 mil gap in SLO compared favorably to rated power and flow.

Therefore, Unit 1 operation will be restricted to 80% recirculation pump speed during SLO.

7.0 RELOAD ANALYSIS ENC performed a review of SLO for SSES Unit 1 with ENC 8x8 fuel. Since ENC and GE 8x8 fuel designs are very similar and both two-loop analyses show similar results including yielding comparable MCPR limits, the GE analyses is also applicable to ENC 8x8 fuel.

A review of the Anticipated Operational Occurrences was performed for SLO. The comparison of the rated power and SLO analyses performed by GE show the rated power analyses bounds SLO. This occurs as the transient delta CPR is smaller for SLO then at rated power. In addition, the operating limit for lower powers is the same or greater than at rated power. Since ENC 8x8 fuel is comparable to GE 8x8 fuel, similar results would be expected for ENC 8x8 fuel. Therefore, the operating MCPR limits established for two-loop operation with ENC 8x8 fuel will be conservative for SLO.

The rod withdrawal error analyses takes credit for the rod block and scram trip systems. For SLO the procedure established by GE to correct for the back flow through the inactive jet pumps is also applicable for ENC 8x8 fuel. This results in the correct total drive flow used in the rod block and scram trip systems. Consequently, the ENC two-loop rod withdrawal error analysis is conservative for SLO.

GE performed a review of the safety limit for SLO. The result was a 0.01 increase in the safety limit (1.06 to 1.07) to account for the increased flow measurement and TIP noise measurement uncertainties in SLO. GE also requires a 0.01 increase in the safety limit for reloads. ENC's evaluation of these uncertainties shows the increase in the uncertainties is also applicable to ENC fuel. Therefore, the safety limit for ENC will also increase by 0.01 (1.06 to 1.07) in SLO.

A review of the MAPLHGR limits was performed by ENC. For two-loop operation, ENC methodology yields allowed MAPLHGR limits somewhat greater than GE. Therefore, an ENC analysis performed for SLO operation would be expected to yield somewhat higher MAPLHGR limits than GE. Consequently, the GE SLO multiplier factor of 0.81 on the GE high enriched two-loop MAPLHGR limit is also conservative to use on the ENC fuel for SLO.

ENC 8x8 fuel is hydraulically compatible 'with GE 8x8 fuel. Since SSES Unit 1 Technical Specifications have implemented surveillance requirements for detecting and suppressing power oscillations, core stability will not be affected with ENC 8x8 fuel.

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