ML20057B844
| ML20057B844 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 09/14/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20057B843 | List: |
| References | |
| NUDOCS 9309240059 | |
| Download: ML20057B844 (9) | |
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UNITED STATES 5~
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WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0. 184 TO FACILITY OPERATING LICENSE NO. DPR-56 PHILADELPHIA ELECTRIC COMPANY PUBLIC SERVICE ELECTRIC AND GAS COMPANY DELMARVA POWER AND LIGHT COMPANY
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ATLANTIC CITY ELECTRIC COMPANY PEACH BOTTOM ATOMIC POWER STATION. UNIT 3
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1 DOCKET NO. 50-278
1.0 INTRODUCTION
1 By letter dated April 1, 1993 (Reference 1), as supplemented by letters dated i
April 7, July 16 (Reference 2), and August 20, 1993 (Reference 11), the Philadelphia Electric Company, (PECo, the licensee) submitted a request for changes to the Peach Bottom Atomic Power Station (PBAPS), Unit Nos. 2 and 3, Technical Specifications (TSs).
The requested changes implement an expanded power-to-flow operating domain supported by the Average Power Range. Monitor (APRM), Rod Block Monitor (RBM), Technical Specifications Improvements / Maximum j
Extended Load Line Limit (ARTS /MELLLA) program and analyses. The April 7, July 16, and August 20, 1993, letters provided additional clarifying information that did not change the initial no significant hazards consideration determination.
The request proposed three fundamental changes:
(1) Deletion of the flow-biased APRM scram and rod block trip setpoint setdown requirements; (2) Revision of flow-biased APRM scram and rod block trip equations to expand the power-to-flow operating domain; and, (3) modifications to RBM trip set-points. The changes involve hardware modifications, procedure changes and associated TS changes.
The first change, eliminating APRM setpoint setdown, involves several thermal-hydraulics associated updates made to ensure that the safety limit minimum critical power ratio (MCPR) and fuel thermal-mechanical design bases are not violated. These are:
.a.
Elimination of reference to k,, the MCPR flow adjustment factor, b.
Introduction of power and flow dependent adjustments to the maximum average planar linear heat generation rate (MAPLHGR) and MCPR limits,-
c.
Revision of Core Operating Limits Report (COLR) documentation requirements to include parameters used to determine thermal operating limits, and d.
Removal of the fraction of rated power (FRP) and the maximum fraction of limiting power density (MFLPD) definitions since they are used only in relation to the APRM setpoint setdown.
9309240059 30914 PDR-ADDCK 05000278.-
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4 The changes to the APRM scram and rod block trip equations require I
modification to the APRM rod block electronics.
The RBM trip setpoint changes include alterations to the RBM trip logic.
In support of its request, the licensee has submitted the proposed TS changes, a brief explanation of the changes, and a General Electric (GE) topical report (Reference 3) describing in detail the ARTS /MELLLA program for PBAPS.
In order to further support the proposed ARTS /MELLLA changes, the design basis loss-of-coolant accident (LOCA) for PBAPS was analyzed using SAFER /GESTR methodology. The licensee had previously expressed its intention to implement SAFER /GESTR (Reference 4). The GE LOCA analysis topical report (Reference 5) was submitted by letter dated April 7,1993, and supplemental information was furnished by the licensee in Reference 2.
2.0 EVALUATION These proposed changes for PBAPS are common for GE boiling water reactors.
They have become part of standard operating flexibility options as described in the GE standard application for reactor fuel (Reference 6).
The NRC staff has previously reviewed and approved the ARTS /MELLLA changes for several i
boiling water reactors (BWRs).
The methodologies used for the safety analyses justifying the changes and establishment of new operating limits have been previously reviewed and approved by the staff and are documented in Safety Evaluations for Hatch (Reference 9) and Monticello (Reference 10).
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operating region and the APRM and RBM changes proposed for PBAPS are similar l
to equivalent changes approved previously by the staff in Reference 9 and
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Reference 10.
i i
Since the submittal for PBAPS includes changes which have become standard and have been well considered for other plants, only a brief description of them is included here. More detailed information is available in Reference 9 and Reference 10. Aspects of the changes or analyses specific to PBAPS are discussed in more depth, although all of the analyses considered previously were reexcmined for this review.
2.1 ARTS /MILLLA 2.1.1 Proaram Descriction The MELLLA mode of operation and the ARTS program include the following changes:
a.
The operating power to flow map is expanded to allow operation above the rated rod line.
b.
A power dependent minimum critical power ratio (MCPR) is implemented to complement the updated RBM system.
3 c.
Power and flow dependent thermal limits are introduced to replace the APRM trip setdown requirement.
These are power and flow dependent MAPLHGR and MCPR multiplication factors: MAPLHGR(P), MAPLHGR(F), MCRP(P), and MCPR(F).
d.
Power dependent RBM trips replace flow biased trips. RBM inputs are reassigned to improve system characteristics and operability.
e.
An updated rod withdrawal error analysis is presented to account for system changes and more closely reflect plant conditions.
f.
RBM electronics are updated to produce a trip signal which is a function of the percentage increase from the initial signal.
Fuel performance transient analyses, mechanical evaluation of the reactor internals, structural vibration, LOCA analyses, containment loads evaluations and rod withdrawal error analyses are all required to justify the above ARTS /MELLLA changes.
The thermal limits introduced under ARTS program are specified to protect fuel during anticipated operational occurrences (A00s).
The plant thermal limits used in the PBAPS analyses are intended to remain applicable to future reload cycles, including GE fuel designs through Gell t
type fuel.
Future changes in fuel designs, analytical methods or plant configurations may require confirmatory verification.
Plant-specific portions of the ARTS limits for PBAPS were developed based on the Unit 2 Cycle 10 core configuration.
Similarity of fuel types and plant configuration makes these ARTS plant-specific limits applicable to both PBAPS Units 2 and 3.
2.1.2 MELLLA Analyses PBAPS is currently licensed to operate in the extended load line limit (ELLL) region above the rated rod line along the 108% APRM rod block line to the 100% power /87% flow (100P/87F) point on the power-to-flow map. The MELLLA analysis expands the operating domain along the 121% rod line to 100P/75F, allowing rated power operation at any flow between 75% and 100%.
This expansion extends the analyzed operating domain to the 121% rod line. The clamped values of the flow biased APRM flux scram and APRM rod block trips will be inserted at 75% flow.
To justify operation of PBAPS in the MELLLA domain, core-wide anticipated operational occurrences (A00) were analyzed in Reference 3 to determine the limiting MCPR requirement, peak vessel pressure, and stability effects. The events chosen as potentially limiting and re-evaluated in detail are the same events analyzed for previous ARTS /MELLLA submittals reviewed by the staff in Reference 9 and Reference 10. These include; generator load rejection without bypass, turbine trip without bypass, feedwater controller failure, inadvertent high-pressure coolant injection (HPCI), and loss of feedwater heating.
Inputs for analyses corresponding to the 100P/75F condition were developed from the PBAPS Unit 2 Cycle 10 information.
The methods used were consistent with the bases of the Cycle 10 reload submittal. The analyses indicate that the generator load rejection event was most limiting for MELLLA conditions.
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a 2 Further, the results show that for the events examined, the operating limit MCPRs for rated conditions (100P/100F) bound those for MELLLA conditions.
Subsequent reload licensing reviews will include examination of cycle-specific data in the MELLLA region.
Vessel overpressure protection was demonstrated by analysis of the main steam line isolation valve (MSIV) closure with flux scram.
Initiation of this event from the MELLLA region yielded results that comply with the American Society of Mechanical Engineers Pressure Vessel Code.
1 As is the case for other BWRs operating under ARTS /MELLLA, PBAPS will maintain compliance with NRC Bulletin 88-07, Supplement 1, " Power Oscillations in Boiling Water Reactors." The added operating region does not alter compliance i
with the stability requirements.
Although minor differences from equivalent MELLLA analyses are included for i
sensitivity study and future consideration, the analyses presented for PBAPS operation in the MELLLA region yield acceptable results and conform to those previously evaluated by the staff and are acceptable.
2.1.3 ARTS Analyses To justify operating PBAPS under the ARTS program, analyses of A00s done in support of MELLLA were used to determine the off-rated power and flow dependent MCPR and MAPLHGR functions.
Flow run-out events were also analyzed to assure that the flow dependent MCPR limit is sufficient to prevent violation of the safety limit MCPR (SLMCPR) during recirculation flow increase events.
Rod withdrawal error (RWE) analysis was performed to determine setpoints for the updated RBM system. A generic statistical RWE examination was validated for Gell fuel designs for PBAPS. A LOCA analysis, discussed in Section 2.2 of this evaluation, was performed to verify the flow dependent MAPLHGR limits.
i PBAPS specific analyses were performed to confirm the applicability of generic power and flow dependent MCPR and MAPLHGR limits taken from the ARTS data base. These plant limits were selected to remain valid through future reloads using Gell fuel and currently approved analysis methods. The ARTS analyses used current Cycle 10 inputs along with bounding values for core power, maximum core flow, and reduced feedwater temperature (for the feedwater controller failure analysis).
Overall, the ARTS analyses and the proposed changes to the APRM and RBM systems parallel ARTS submittals for other BWRs which were accepted by the staff (Reference 9 and Reference 10). An important exception was the SAFER /GESTR LOCA analysis, which required additional study, as discussed in Section 2.2.
The ARTS hardware updates proposed for PBAPS are the same as those previously reviewed by the staff.
However, the GE report states that the adjustable trip time delay option t for the RBM will not be used for PBAPS. Although the a
1
. option is included with the hardware, sufficient RWE analysis was not performed to allow its use. The suggestion made by the GE report that the tez setting could be used to bypass the RBM system is counterto previous staff findings (Reference 9) and is not permitted. Any future use of this time delay setting will require the evaluation of further analysis, as discussed in the GE report.
Based on the review of the Peach Bottom specific ARTS analyses and changes described above and comparison to the generic ARTS analyses and changes evaluated in Reference 9 and Reference 10, the staff finds the proposed implementation of system changes associated with the ARTS updates, including the hardware modifications and proposed analytical limits, with the exception of the RBM adjustable trip time delay option described in the previous paragraph, to be acceptable.
2.2 SAFER /GESTR LOCA Analysis To ensure that the 10 CFR 50.46 LOCA criteria were met by the flow dependent MAPLHGR multipliers, a LOCA analysis was performed using the GE SAFER /GESTR LOCA methodology. Application of SAFER /GESTR to PBAPS was detailed in a GE report (Reference 5) and was evaluated as part of the ARTS /MELLLA application.
Requirements for the use of SAFER /GESTR were established in the Topical Report Evaluation contained in Reference 7.
The evaluation includes the stipulation that the plant-specific peak cladding temperature (PCT) versus break size curve match the trend of the generically determined curve. The nominal PCT (PCT This
) curve is determined using best-estimate values of plant response.
curve establishes the limiting bred (normally the large break LOCA) which is used for subsequent calculations.
Licensing basis PCT (PCT is determined for the limiting case. Upper bound PCT (PCT ) is then deYerm)ined g
us to confirm the conservatism of the (PCT generic report uses assumptions arising,Tro)m.The analysis presented in the c
conditions based on the large break event. The requirements of the Topical Report Evaluation ensure that plant LOCA response does not significantly diverge from the generic LOCA response and possibly invalidate application of SAFER /GESTR LOCA analysis.
Results of break calculations presented in the PBAPS PCT vs. break size plot in Figure 5-1 of Reference 5 are noticeably different from the generic BWR 4 break spectrum (Figure 3.3 of Reference 8). The PBAPS nominal PCT (PCT, for a small break (0.08 ft ) LOCA in the discharge line is greater than $)at z
for the normally limiting large break.
The PBAPS report attributes the difference to a lower ADS capacity relative to vessel volume for PBAPS as well as relaxed ECCS parameters used for this particular analysis.
Additional analysis submitted by the licensee (Reference 2) describes a determination of the PCT for the small break to validate the PCT value determined in the originD report and ensure that the large breakNA is the limiting event. The process applied is based on a propagation of errors procedure described in the generic report (Reference 8) and indicates that a margin of 35'F exists between the PCT and PCT,, for the small break.
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analysis, largely based on the generic SAFER /GESTR evaluation for BWR 4 plants, is considered satisfactory and yielded adequate margin to validate the licensing basis PCT, ppg.
Thus, the application of SAFER /GESTR to PBAPS is considered acceptable.
However, changes to plant operating conditions which could affect LOCA analyses should consider possible impacts on the small break PCT calculation us to ensure that adequate margin is maintained to the PCT, ppg.
As discussed in Reference 3, a determination of containment response under revised assumptions introduced by MELLLA operation was conducted coincident with the LOCA analysis.
Short term containment response was examined for MELLLA thermal-hydraulic conditions, including current rated power and feedwater temperature. The results indicated that the maximum drywell airspace temperature would exceed the design value of 281*F for about 10 seconds at the beginning of the event. The peak pressure, however, would remain below the design limit of 56 psig. The PBAPS UFSAR specifies that the maximum drywell temperature is limiting coincident with the maximum internal pressure limit.
Since the high temperature is expected to be of short duration and the pressure limit is not approached, the staff agrees that drywell structural integrity is not threatened by MELLLA operation.
- However, changes in the parameters associated with this analysis, especially core power or feedwater temperature, may necessitate re-evaluation of the containment response to ensure that containment integrity is not threatened.
With the qualifications discussed above, the application of SAFER /GESTR LOCA methodology to PBAPS Units 2 and 3 is acceptable.
2.3 TECHNICAL SPECIFICATIONS Changes to PBAPS limits and operability requirements in the TS are necessary to implement ARTS /MELLLA. The proposed TS changes follow:
a.
Definitions are added to Section 1.0 for down-scale trip setpoint (DTSP),
high power trip setpoint (HPTS), intermediate power trip setpoint (ITSP),
low power trip setpoint (LTSP), MAPLHGR flow factor, and power dependent MAPLHGR multiplier. The definition for MCPR is revised to include MCPR(F) and MCPR(P).
b.
Limiting Safety System Setting Section 2.1 is changed to revise the APRM flux scram and APRM rod block trip setting equations. Numerical values for core flow are removed, and maximum values for the scram and rod block' trips are added (120 and 108 percent of rated power, respectively). The setpoint setdown requirements, along with the fraction of rated thermal power (FRP) and maximum fraction of limiting power density (MFLPD) definitions are removed.
c.
The Safety Limit Bases Section 1.1 References are updated to include the GE ARTS /MELLLA analysis report (Reference 3).
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d.
Figure 1.1-1, ~ entitled, "APRM Flow Bias Scram Relationship to Normal Operating Conditions," (the power-to-flow operating map) is revised; to j
include the MELLLA region and the updated-APRM limits.
1 e.
Explanations for setpoint setdown are removed from Bases Section 2.1.A, l
and a reference is included to power and flow dependent MCPR factors l
located in the COLR.
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f.
Surveillance Requirement (SR) 4.1.B, to determine MFLPD and employ l
setpoint setdown specifications, is deleted, as is its explanation in-
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Bases Section 4.1.B.
g.
Table 3.1.1, Reactor Protection System (SCRAM) Instrumentation Requirement, incorporates the revised APRM high flux scram equation.
h.
Table 3.2.C, Instrumentation That Initiates Control Rod Blocks, is changed to include new APRM upscale, rod block monitor and rod block monitor down-scale trip values, and remove mention of setpoint setdown.
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- i. Note 11 is added to Table 3.2.C to indicate that the values of HTSP, ITSP,
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LTSP, and DTSP are included in the Core Operating Limits Report (COLR).
- j. Surveillance Requirement 4.5.I includes a reference to the COLR for the MAPLHGR(F) and MAPLHGR(P) multipliers.
k.
Limiting Condition for Operation (LCO) 3.5.K includes the MCPR(F) and MCPR(P) multipliers ana refers to the COLR for their values.
1.
Bases Section 3.5.1 refers to the COLR'for APLHGR values and indicates that the values for MAPFAC(F) and MAPFAC(P) adjustment factors are in the COLR.
m.
Bases Sections 3.5.K, 3.5.L and 3.5.M are; updated to include the GE ARTS /MELLLA analysis report (Reference 3).
Bases Section 4.5.L is rewritten to eliminate the K, factor and describe n.
the power and flow dependent MCPR limits, MCPR(F) and MCPR(P).
i o.
Routine Reports Section 6.9.1(e), detailing the contents of the COLR, is -
updated to list core flow and power adjustment factors and the upscale-power biased RBM setpoints. K is eliminated, and Reference 3 is included i
in a list of analytical method,s used for core operating limits determination.-
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Based upon the acceptance of the methods and results of the ARTS /MELLLA for j
PBAPS as discussed in Section 2 of this evaluation, these TS changes are acceptable.
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0 By letter dated August 20, 1993, the licensee submitted revisions to the Unit 2 TS Pages 4, 20, and 140b, and the Unit 3 TS Pages 4 and 9.
The revisions corrected typographical errors contained in the TS pages contained in the April 1, 1993, submittal.
The revisions also updated the affected pages to reflect Unit 2 TS Amendment 178 and Unit 3 TS amendments 181 and 183, which were issued subsequent to the licensee's April 1, 1993, application.
The revisions are editorial in nature and ensure that the amendment described in this SE accurately reflects previous TS amendments and, therefore, are acceptable.
The licensee's application proposed the ARTS /MELLLA TS changes for both Units 2 and 3.
The application requested that the amendments be effective upon completion of the ARTS /MELLA modifications. The licensee plans to implement the ARTS /MELLLA modifications on Unit 3 during Refueling Outage 3R09 scheduled i
for the fall of 1993 and on Unit 2 during Refueling Outage 2R010 scheduled for the fall of 1994.
To prevent confusion between the effective date for the Unit 2 ARTS /MELLLA amendment and the effective date of subsequent amendments i
that may affect the same TS pages. The staff is issuing the Unit 3 ARTS /MELLLA amendment at this time and will issue the Unit 2 ARTS /MELLLA amendment just prior to Refueling Outage 2R010.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Pennsylvania State i
official was notified of the proposed issuance of this amendment.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined i
that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released i
offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a i
proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (58 FR 39058). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need ba i
prepared in connection with the issuance of the amendment.
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5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be enc' angered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
J. Donoghue Date: september 14, 1993
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- c. REFERENCES 1.
Letter from G. A. Hunger, Jr., PECo, to NRC, dated April 1, 1993 Peach Bottom Atomic Power Station, Units 2 and 3, Technical Specification Change Request 93-01.
2.
Letter from G. A. Hunger, Jr., PECo, to NRC, dated July 16, 1993, Peach Bottom Atomic Power Station, Units 2 and 3, Response to Request for Additional Information on SAFER /GESTR LOCA Methodology.
3.
NEDC-32162P, Revision 1, " Maximum Extended Load Line Limit and ARTS Improvement Program Analyses for Peach Bottom Atomic Power Station Units 2 and 3," February 1993, (General Electric proprietary information).
4.
Letter from G. A. Hunger, Jr., PECo, to NRC, dated March 18, 1993, Peach Bottom Atomic Power Station, Units 2 and 3, Adoption of SAFER /GESTR LOCA t
Methodology.
5.
NEDC-32163P, " Peach Bottom Atomic Power Station Units 2 and 3 SAFER /GESTR-LOCA Loss-of-Coolant Accident Analysis," January 1993, (General Electric proprietary information).
6.
NEDE-24011-P-A-10-US, " General Electric Standard Application for Reactor Fuel," April 1991 (General Electric proprietary information).
7.
Letter from C. O. Thomas, NRC, to J. F. Quirk, GE, dated June 1, 1984, Accepting GE Topical Report NEDE-23785 Revision 1, Volume III(P), "The GESTR-LOCA and SAFER Models for the Evaluation of the Loss-of-Coolant Accident."
8.
NEDE-23785-1-PA, The GESTR-LOCA and SAFER Models for the Evaluation of the Loss-of-Coolant Accident, Volume III, Revision 1, October 1984, (General Electric proprietary information).
9.
Safety Evaluation by the Office of Nuclear Reactor Regulation Supporting Amendment No. 39 to Facility Operating License No. NPF-5, Edwin I. Hatch Nuclear Plant, Unit No. 2, Docket No. 50-366, dated July 13, 1984
- 10. Safety Evaluation by the Office of Nuclear Reactor Regulation Supporting I
Amendment No. 29 to Facility Operating License No. DPR-22, Monticello Nuclear Generating Plant, Docket No. 50-263, dated November 16, 1984.
- 11. Letter from G. A. Hunger, Jr., PECo, to NRC, dated August 20, 1993, Peach i
Bottom Atomic Power Station, Units 2 and 3, Revised Technical l
Specification Change Request.