ML20072C758
| ML20072C758 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 08/10/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20072C753 | List: |
| References | |
| NUDOCS 9408180084 | |
| Download: ML20072C758 (10) | |
Text
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S NUCLEAR REGULATORY COMMISSION E
f WASHINGTON. D.C, 20555 0001
%.....,5 SAFETY EVALUATION BY THE OFFICE OF NVCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 192 TO FACILITY OPERATING LICENSE N0. DPR-44 PHILADELPHIA ELECTRIC COMPANY P_VBLIC SERVICE ELECTRIC AND GAS COMPANY DELMARVA POWER AND LIGHT COMPANY ATLANTIC CITY ELECTRIC COMPANY PEACH BOTTOM ATOMIC POWER STATION. UNIT 2 DOCKET N0. 50-277
1.0 INTRODUCTION
By letter dated April 1,1993 (Reference 1), as supplemented by letters dated April 7, July 16 (Reference 2), and August 20, 1993 (Reference 11), and June 8,1994 (Reference 12), the Philadelphia Electric Company, (PEC0, the licensee) submitted a request for changes to the Peach Bottom Atomic Power Station (P8APS), Unit Nos. 2 and 3, Technical Specifications (TS).
The requested changes implement an expanded power-to-flow operating domain supported by the Average Power Range Monitor (APRM), Rod Block Monitor (RBM),
TS Improvements / Maximum Extended Load Line Limit (ARTS /MELLLA) program and analyses. The April 7, July 16, and August 20, 1993, and June 8, 1994, letters provided additional clarifying information that did not change the initial no significant hazards considerations determination.
The amendment for Unit 3 was issued on September 14, 1993 (Amendment No. 184).
The Unit 2 amendment was not issued at that time because the licensee would not be able to implement the amendment at Unit 2 until the latter part of 1994.
This safety evaluation is identical to the one issued for Unit 3, except for an additional discussion on PEC0's June 8,1994 supplemental letter.
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.
9408180084 940810 PDR ADOCK 05000277 p
N 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.
Errata sheets for Reference 3 were provided in Reference 12.
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 boiling water reactors (BWRs), including Unit 3 of PBAPS as noted above.
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).
The new operating region and the APRM and RBM changes proposed for PBAPS, Unit 2 are similar to equivalent changes approved previously by the staff in Reference 9 and Reference 10.
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 in this evaluation. 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 reexamined for this review.
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 cycle specific 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.
The removal of certain cycle-specific factors and additional references to the COLR will ensure that the values of parameters for operation are determined consistent with reload safety analyses.
. i The changes to the APRM scram and rod block trip equations require modification to the APRM rod block electronics. The RBM trip setpoint changes include alterations to the RBM trip logic.
These hardware changes have been I
accepted in previous ARTS /MELLLA reviews by the staff (References 9 and 10).
2.1 ARTS /MELLLA 2.1.1 Proaram Description 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 MCPR is implemented to complement the updated RBM system.
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), MCPR(P), and MCPR(F).
d.
The following power dependent RBM trips replace flow biased trips; downscale trip setpoint (DTSP), high trip setpoint (HTSP), and intermediate trip setpoint (ITSP).
RBM inputs are reassigned to improve system characteristics to provide better response to rod motion.
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.
t 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).
i The plant thermal limits used in the PBAPS analyses are intended to remain applicable to future reload cycles, including.GE fuel designs through Gell 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, Unit 2 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 A00s 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.
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.
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 with the stability requirements.
Although minor differences from equivalent MELLLA analyses are included for 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 Ana1Yses 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.
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.
These include an upscale trip function related to core power rather than a flow biased trip, as well as a downscale trip used to detect abnormally low signals.
The GE report (Reference 3) states that the adjustable trip time delay option t for the RBM will not be used for PBAPS.
AlthoughtheoptionisincludedwitNthehardware,thereportstatesthat sufficient RWE analysis was not performed to allow its use. Although the GE report suggests that the t setting could be used to bypass the RBM system, this procedure is not permdted without staff review and approval (see 4
Reference 9). The licensee has not requested to utilize the adjustable trip time delay option t Any future request to use the time delay option will q2 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 implementation of system changes associated with the ARTS updates as proposed by the licensee 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.
) curve is determined using best-estimate values of plant response.
This curve establishes the limiting break (normally the large break LOCA)
Licensing basis PCT (PCT is which is used for subsequent calculations.
Upper bound PCT (PCT ) is then deYerm)ined g
determined for the limiting case.
to confirm the conservatism of the (PCT The analsis presented in the generic report uses assumptions arising,Tro)m.
g 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,b. )
z at 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 originUI report and ensure that the large break"ET)EA 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.
The analysis, largely based on the generi$ SAFER /Gb 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.
i
. 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 RBM associated trip settings DTSP, HPTS, ITSP, and LTSP. These additions are acceptable based on the discussion in Section 2.1.1 of this evaluation.
Also added are the definitions for MAPLHGR flow factor, and power dependent MAPLHGR multiplier, and the definition for MCPR is revised to include MCPR(F) and MCPR(P).
These changes are acceptable based on the discussion in Sections 2.1.1 and 2.1.3 of this evaluation.
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).
These changes are acceptable based on the discussion in Section 2.1.2 of this evaluation.
The setpoint setdown requirements, along with the fraction of rated thermal power (FRP) and maximum fraction of limiting power density (MFLPD) definitions are removed. These revisions are acceptable based on the discussion in Section 2.0 of this evaluation.
c.
The Safety Limit Bases Section 1.1 References are updated to include the GE ARTS /MELLLA analysis report (Reference 3).
d.
Figure 1.1-1, entitled, "APRM Flow Bias Scram Relationship to Normal Operating Conditions," (the power-to-flow operating map) is revised to include the MELLLA region and the updated APRM limits.
This revision is acceptable based on the discussion in Section 2.1.2 of this evaluation.
e.
Explanations for setpoint setdown are removed from Bases Section 2.1.A, and a reference is included to cycle dependent power and flow dependent MCPR factors located in the COLR.
These revisions are acceptable based on the discussion in Sections 2.0, 2.1.1, and 2.1.3 of this evaluation.
f.
Surveillance Requirement (SR) 4.1.B, to determine MFLPD and employ setpoint setdown specifications, is deleted, as-is its explanation in Bases Section 4.1.B.
This revision is acceptable based on the discussion in Section 2.0 of this evaluation.
g.
Table 3.1.1, Reactor Protection System (SCRAM) Instrumentation Requirement, incorporates the revised APRM high flux scram equation.
This revision is acceptable based on the discussion in Section 2.1.2 of this evaluation.
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. 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. These revisions are acceptable based on the discussion in Sections 2.0 and 2.1.1 of this evaluation.
i.
Note 11 is added to Table 3.2.C to indicate that the cycle specific values of HTSP, ITSP, LTSP, and DTSP are included in the Core Operating Limits Report (COLR).
This change is acceptable based on the discussion in Section 2.0 of this evaluation.
j.
Surveillance Requirement 4.5.I includes a reference to the COLR for the MAPLHGR(F) and MAPLHGR(P) multipliers. This change is acceptable based on the discussion in Section 2.0 of this evaluation.
k.
Limiting Condition for Operation (LCO) 3.5.K includes the MCPR(F) and MCPR(P) multipliers and refers to the COLR for their cycle specific values. These changes are acceptable based on the discussion in Sections 2.0 and 2.1.3 of this evaluation.
1.
Bases Section 3.5.I refers to the COLR for APLHGR values and indicates that the cycle specific values for MAPFAC(F) and MAPFAC(P) adjustment factors are in the COLR. This change is acceptable based on the discussion in Section 2.0 of this evaluation.
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),
factor and describe Bases Section 4.5.L is rewritten to eliminate the K,d MCPR(P).
n.
the power and flow dependent MCPR limits, MCPR(F) an These revisions are acceptable based on the discussion in Sections 2.1.1 and 2.1.3 of this evaluation, 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.
Locating these parameters in the COLR is consistent with the approach of eliminating cycle specific parameters from the technical specifications.
K is eliminated, and Reference 3 is included in a list of analytical, methods used for core operating limits determination.
This change is acceptable based on the discussion in Section 2.0 of this evaluation.
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 are editorial in nature and-ensure that the amendment described in this SE accurately reflects previous TS amendments and, therefore, are acceptable.
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In Reference 12, the licensee submitted errata sheets for Reference 3.
The errata sheets corrected the definition of the allowable value for the APRM flow-biased rod block and the analytical trip setpoint for the APRM flow biased flux scram.
These corrections were reviewed by the staff and were determined to appropriately clarify the definitions and were therefore acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Pennsylvania State 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 that the amendment involves no significant. increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (58 FR 39058). The amendment also relates to changes in recordkeeping, reporting, or administrative procedures or requirements. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9) and (10).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
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 endangered 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: August 10, 1994
5 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 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-240ll-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 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 Bottom Atomic Power Station, Units 2 and 3, Revised Technical Specification Change Request.
- 12. Letter from G. A. Hunger, Jr., PEC0, to NRC, dated June 8, 1994, Peach Bottom Atomic Power Station, Units 2 and 3, Submittal of Errata Sheets to General Electric Analyses for Technical Specifications Change Request (TSCR) 93-01 and TSCR 93-12.
.