ML20198H757
| ML20198H757 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 05/27/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20198H720 | List: |
| References | |
| NUDOCS 8605300542 | |
| Download: ML20198H757 (5) | |
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UNITED STATES O
NUCLEAR REGULATORY COMMISSION 3
,j WASHINGTON, D. C. 20555
- e s,,,s SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT N0. 44 TO FACILITY OPERATING LICENSE NO. DPR-22 NORTHERN STATES POWER COMPANY MONTICELLO NUCLEAR GENERATING PLANT DOCKET N0. 50-263
1.0 INTRODUCTION
By letter dated March 7, 1986 (Reference 1) Northern States Power Company (the licensee) proposed to change the Technical Specifications for the Monticello Nuclear Generating Plant to permit its operation for Cycle 12. The proposed changes include administrative changes relating to the previously approved ARTS (APRM/RBM/ Technical Specification)
Improvement Program and operation in an expanded power-flow domain (Reference 4 and 5). In addition, revised MAPLHGR limits are proposed to accommodate a new fuel type (GE-7 barrier fuel) and extended exoosure for some existing fuel.
In the core-related areas of fuel design, thermal-hydraulic design, nuclear design, and safety analyses of postulated accidents and transients, the licensee has relied on the results oresented in the approved General Electric Company (GE) topical report NEDE-24011, " General Electric Standard Application for Reactor Fuel," or GESTAR II (Reference 2).
In addition, the licensee submitted a supplemental reload licensing docunent (Reference 3) which provides results of other analyses necessary to,iustify Cycle 12 operation but which' are not included in GESTAR II.
2.0 EVALUATION 2.1 Fuel Desion
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Fresh fuel assemblies (BP8DRB299L), which are pressurized 8x8 retrofit barrier fuel assemblies, will be loaded for Cycle 12 operation. Since the pressurized 8x8 retrofit barrier fuel has been reviewed by the staff
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and found acceptable (Amendment 13 to Reference 2), we conclude that the fuel assemblies are acceptable for Cycle 12 operation. The 124 new assemblies will reside with 360 irradiated 8X8 assemblies of prior GE designs presently in the core. The fuel designs for the earlier designs have all been found acceptable in connection with the staff review of Reference 2.
2.2 NuclharDesign The nuclear design and analysis of the proposed reload has been performed by the methods described in Reference 2.
Reference 2 has been approved for use in the design and analysis of reloads in boiling water reactors (BWR) and its use is acceptable for this reload. We have reviewed the 8605300542 860527 PDR ADOCK 05000263 p
results of the nuclear design analysis for Monticello Cycle 12 and have determined that, since the nuclear parameters are within the range of those normally obtained.for similar cores and were obtained with acceptable methods, they are acceptable.
2.3 Thermal-Hydraulic Design The ob.iective of the review of the thermal-hydraulic design of the core for Cycle 12 operation is to confirm that the thermal-hydraulic design has been accomplished using acceptable methods, and to assure an acceptable margin of safety from conditions which could lead to fuel damage during normal operation and anticipated transients, and to assure that the core is not susceptible to thermal-hydraulic instability.
The review included the followina areas:
(1) rated minimum critical power ratio (MCPR), and the related changes to the Technical Specifications, and (2) thermal-hydraulic stability. Discussion of the review concernina the thermal-hydraulic design for Cycle 12 operation follows:
(1) Rated MCPR end the Related Technical Specification Chances Power deoendent MCPR limits have been imposed to assure that 99.9 percent of the fuel rods in the core will not experience boiling transition during normal operation and anticipated coerational transients. As stated in Reference 3 the approved safety limit MCPR for the Monticello reload core is 1.07.
The safety limit of 1.07 was used for the Cycle 1? analyses.
In a related matter, the licensee has proposed that four ARTS (Average Power Range Monitor, Rod Block Monitor and Technical Specifications Program) curves be added to the Monticello Technical Specifications to replace a reference to the same curves in a proprietary GE Topical Report (Reference 4). This is an administrative change which we find to be acceptable and appropriate.
To assure that the fuel cladding integrity safety limit MCPR will not be violated during any anticipated transient, the most limiting events have been reanalyzed for this reload (Reference 3) by the licensee, in order to determine which event results in the largest reduction in MCPR. The operating limit MCPR for each fuel type was then established by adding the largest reduction factor in the MCPR to the safety limit MCPR. The operating limit MCPR for Cycle 12 increased by 0.01 over the value for the previous Cycle 11.
We find that, since approved methods (Reference 2) were used and the
.results show an acceptable margin of safety from conditions which could lead to fuel damage during any anticipated operational transient, the thermal-hydraulic design of the Cycle 12 is acceptable. The corresponding changes to Technical Specification y
3.11.C.1. (See Section 2.5) are also acceptable since they are consistent with the Cycle 12 safety analysis.
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(?) Thermal-Hydraulic Stability The results of thermal-hydraulic analyses applicable to previous cycles showed that the maximum core stability decay ratio was 0.63.
The licensee has referenced Generic Letter (GL) No. 86-02 as
,iustification for not performing an additional stability analysis for Cycle 12. GL 86-0?. informs BWR licensees of the technical resolution of Generic Issue B-19 (Thermal-Hydraulic Stability) and cautions licensees to examine each core reload to assure that an acceptable stability margin exists.
Since Monticello is a BWR/3 with a conventional fuel design and operating restrictions which provide a substantial stability margin, the staff concludes that no additional stability analysis is reouired for Cycle 12. A more recent GL 86-09 addresses thennal-hydraulic instabilities in connection with the single loop operating mode. This will be oursued further for Monticello to evaluate the need for future Technical Specification revisions if permanent single 1000 operation (SLOI is proposed.
2.4 Transient and Accident Analvses The licensee reported the results of those events which required a reanalysis to support Cycle 1? operation. All events reanaly7ed showed results consistent with the anplicable criteria. The reanalyses were done in connection wit.h the implementation of the ARTS (APRM/RRM/ Technical Specification) Improvement proaram and operation in an expanded power-flow domain. This implementation for Monticello was approved in Amendment No. 79 to Doeratina License No.
DDR-22 (Reference 5).
t On the basis that approved methods were used to perform the analyses and to obtain input parameters for them and that the results of the accident analysis are acceptable for Cycle 12, we conclude that the transients and accident analyses are acceptable.
2.5 Technical Snecification Chanoes There are three Technical Specification chances for Cycle 17 as discussed i
below:
(i) Addition of ARTS curves
.As discussed in Section 2.3 of this SE the incorporation of four previously accepted curves to the Monticello Technical Specifications is an administrative change nnly and is acceptable.
(2) Addition of New Fuel Type, GE-7 Barrier Fuel j
i MAPLHGR values for the new fuel type (barrier fuel) were added and i
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. proposed MAPLPGR limits were extended to 45,000 MWD /STO for the barrier fuel and selected fuel from a previous cycle (P80RR284LR).
The limitina values of MAPLHGR for different exoosures is determined from the analysis of a pnstulated design basis loss-of-coolant accident (LOCAL. The LOCA analyses were reexamined in connection with the staff review of the ARTS program and it was concluded that acceptable analytical methods were used to assure that the peak cladding temperature would not be exceeded if the ARTS recommendations are followed. Although we find the analytical methods for the LOCA analysis acceptable, the staff has recently reviewed the GE fuel design and analyses process with respect to extended burnuo considerations. The staff specifically reviewed a GE Topical Report on extended burnup evaluation methodology (Reference 6). Our SE is enclosed in the approved version of Reference 6 The results of our evaluation indicated that burnups up to 46,000 MWD /MTV (41,000 MVD/ST) are acceptable.
At hiaher burnups, there is an inadequate data base for rod-to-tie plate clearances. Therefore, additional information will be reouired i
prior to approval of burnup levels beyond 45,000 MWD /STU.
Table 3.11.1 on Technical Specification pace 214 (titled Maximum Averaoe Planar Linear Feat Generation Rate vs. Exposure) was modified to add MAPLHGR values for the new fuel type and also to combine MAPLHGR values for orevious fuel types. This latter com-bination was performed by selecting the most limiting MAPLHGR for each exposure range for the combined fuel types. Since this con-solidation retains the limitino MAPLHGR concept, the change is acceptable.
(3) PCPR Limit Changes 4
The 0.01 change in the MCPR discussed in Section 2.3 of this SE was made in Table 3.11.2 of the proposed Technical Snecifications. At the same time, administrative changes were made to simplify the interpretation of Table 3.11.2 and the ARTS curves. The term operatina limit MCPR was replaced with the term " Rated Minimum Critical Power Ratio" to distinguish between the value for maximum flow rate (100 percent ratedl and values determined from the application of power flow dependent MCPR limits from the ARTS curves.
Since previously approved methodology was used, we find the changes acceptable.
Based on our review we have found that the licensee has used approved methods to analyze the LOCA response of an approved fuel BDADRR209L and to extend the MAPLHGR limits to higher burnuo levels for the new fuel and one existino fuel type (P8DRR2841R). Therefore, this i
proposed amendment to Section 3.11 and related rioures and Tables of the Technical Specifications to reflect the' addition and extension of the MAPLHGR limits for the identified fuel types is acceptable.
1 3.0 ENVIRONMENTAL CONSIDEPATION This amendment inv.olves a change to a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The staff has determined that the amendment involves nn sianificant increase in the amounts, and no sionificant change in the types, of any effluents that may be released offsite and that there is no sianificant increase in individual or cumulative occupati.onal radiation exposure. The Commission has previ-ously issued a proocsed finding that this amendment involves no signi-ficant hazards consideration and there has been no oublic comment on such finding. Accordingly, this amendment meets the eliaihility criteria for categorical exclusion set forth in 10 CrR 51.72(cl(9).
Pursuant to 10 CFR 51.22(bl no environmental impact statenent nor environmental assessment need be prepared in connection with the issuance of this amendment.
4.0 CONCLUSION
The staff has concluded, based on the considerations discussed above, thao.
(1) there is reasonable assurance that the health and safety of the public will not he endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's reaulations and the issuance of this amendment will not be inimical to the common defense and security nor to the health and safety o' the public.
5.0 DEFERENCES 1.
Letter, D. M. Musolf (NSP) to Office of Nuclear Reactor Peculation (USNRC), dated March 7, 1986 (with attachments).
2.
" Generic Reload Fuel Application," NEDE-24011-P-A-7-US, August 1985.
3.
Supolemental Reload Licensing Submittal for Monticello Nuclear Generatino Plant Reload 11 (Cycle 12), 23A4754, February 1986.
4.
NEDC-30497 " General Electric BWR Licensino Report: Averace Power Range Monitor, Rod Block Monitor and Technical Specification Improvement (ARTS) Procram for Monticello Nuclear Generatina Plant,"
April 1984 5.
Letter, V. Rooney (NRC) to D. M. Musolf (NSPCo) dated November 16, 1984 transmitting Amendment No. 29 to License No. DPR-22 (with e'nclosures).
6.
AED0-22148-A, " Extended Burnun Evaluation Methodoloay," General Electric Licensing Topical Report, February 1986.
Principal Contributor:
M. McCoy Dated:
May 27,1986.
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