ML20039G295
| ML20039G295 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 12/23/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20039G293 | List: |
| References | |
| NUDOCS 8201180011 | |
| Download: ML20039G295 (6) | |
Text
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.,i UNITED STATES
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NUCLEAR REGULATORY COMMISSION
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j WASHINGTON, D. C. 20555 Qed.
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMEN 0 MENT N0. 69 TO FACILITY LICENSE N0. DPR-30 COMMONWEALTH EDISON COMPANY AND IOWA-ILLINDIS. GAS AND ELECTRIC COMPANY QUAD CITIES NUCLEAR POWER STATION UNIT NO. 2 DOCKET NO. 50-265
1.0 INTRODUCTION
By letter dated July 27, 1981 the licensee, Comonwealth Edison Company (CECO), proposed changes to the Technical Specifications (TSs) for Quad Cities Unit 2 (see reference 1). These changes are required to support future reloads for Quad Cities Unit 2 in accordance with the provisions of 10 CFR 50.59 and because the barrier fuel demonstration incorporates features not previously addressed and because of the initial application of the ODYN transient analysis code to the upcoming operating cycle.
Also, in support of the reload application, the licensee provided a supplemental reload submittal for Quad Cities Unit 2 Reload 5 (Cycle 6) dated August 21, 1981 (see reference 2).
For Reload 5, Cycle 6, 80 bundles of precressurized General Electric (GE) 8x8 retrofit fuel (P8x8R) and 144 bundles of barrier fuel (see reference 5), both of standard nuclear design, will be used. Descriptions of the nuclear and mechanical designs of this fuel are contained in references 3, 4 and 5.
Reference 3 also contains a complete set of references to topical reports which describe the GE analytical methods for nuclear, thermal-hydraulic transient and accident calculations and information regarding the applicability of these methods to cores containing a mixture of fuels.
The use and safety implication of prepressurized fuel have been found acceptable in reference 4 The conclusions of reference 6 found that the methods of reference 3 were generally applicable to prepressurized fuel.
Therefore, unless otherwise specified, reference 3, as supported by reference 6, is adequate justification for the current application of prepressurized fuel both for the barrier and nonbarrier fuel. Other aspects of the use of the barrier fuel demonstration bundles are also considered.
2.0 EVALUATION We have reviewed the licensee's application and the associated proposed TS changes. The reload application follows the procedure described in reference 3, " Generic Reload Fuel Application." The thermal-hydraulic models and methodology used are those described in references 3 and 7.
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8201180011 811223 PDR ADOCK 05000265 P
2 2.1 Safety Limit MCPR; Thermal Hydraulics The safety limit minimum critical power ratio (MCPR) is to assure at least 99.9% of the fuel rods in the core are not expected to experience boiling transition during anticipated coerational transient events.
As stated in reference 3, the safety limit MCPR (SLMCPR) is 1.07 for the core with retrofit 8x8 fuel, for both barrier and nonbarrier fuel. This i
limit has previously been found to be acceptable, as it is in this application.
2.2 Ocerating Limit MCPR; Use of ODYN Code The most limiting operational transients for Cycle 6 for Quad Cities Unit _2 have been analyzed by the licensee to determine which event could potentially result in the largest reduction in the initial critical power ratio (aCPR). The ACPR values given in Section 11 of reference 2 are plant-specific values which include results for the transients calculated by using the ODYN methods (see references 7 and 8).
The maximum value of aCPR resulting from the limiting transient, the generator load rejection without bypass transient, is 0.35 for Cycle 6 as compared to 0.23 for Cycle 5 (refs. 5 and 6). The large difference of aCPR for this transient is due to the use of the ODYN methods compared to the REDY methods used in Cycle 5.
The calculated ACPRs were adjusted to reflect either Option A or Option B ACPR by employing the conversion method described in references 7 and 8.
The initial MCPRs are then determined by adding the aCPRs to the safety limit. Section 11 (reference 2) presents both the initial MCPRs for the nonpressurization events and adjusted initial MCPRs (Option A and Option B) for pressurization events. The maximum initial MCPRs -(0ption A and B) in Section 11 are specified as the operating limit MCPRs and are incorporated into the TSs. We have reviewed the operating limit MCPR results discussed above. These results are more limiting for Cycle 6 than for Cycle 5.
We find these results acceptable.
The operating limit MCPR TS has been modified to include an Option B format where the operating limit MCPR varies with the measured scram time. The operating limiting MCPRs are incorporated in TSs 3.3.C/4.3.C and 3.5.K.
2.3 Thermal-Hydraulic Stability The results of the thermal-hydraulic analysis (ref. 2) show that the maximum thermal-hydraulic stability decay ratio is 0.53 for Cycle 6 as compared to 0.52 for Cycle 5.
Since operation in the natural circulation mode is prohibited by TS 2.1.A.4, there is additional margin to the core thermal-hydraulic stability, and we find the stability results acceptable for Cycle 6 operation.
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3 2.4 ECCS Evaluation: MAPLHGR Limits The previously approved reference document NEDO 24146A (see reference 12) contains an approved ECCS analysis for Quad Cities Unit 2, and continues to serve as the basis for generation of MAPLHGR limits for new fuel types.
New MAPLHGR limits for the four barrier fuel types being loaded in the core for Cycle 6 are based on Addenda to reference 12 and were provided in the licensee's submittal (see reference 1). A non-barrier fuel type which is otherwise identical to one of the four barrier fuel types is also being loaded in the Cycle 6 core. The barrier fuel (of that type) MAPLHGR limits apply directly to the non-barrier fuel for the otherwise identical design.
MAPLHGR limits to non-prepressurized fuel have previously been conservatively applied to prepressurized fuel because of the unavailability of the slightly relaxed prepressurized MAPLHGR limits. The prepressured MAPLHGR limits are now available and are included for Cycle 6.
2.5 Pressure Safety Limit Changes Due to ATWS RPT As of January 1,1981, Quad Cities Unit 2 has had a recirculation pump trip (RPT) installed and implemented to mitigate the effects of an anticipated transient without scram (ATHS). While this modification reduces peak pressures for transients without scram, it also has the effect of increasing the peak pressurization for a severe transient with scram, such as load reject without bypass or a main steam isolation valve (MSIV) closure without valve position trip. However, pressurization transients which do cause the RPT setpoint (1250 psig) to be exceeded can cause higher steamdome pressures, where the measured vessel pressure limit is increased from 1325 psig to 1345 psig. The vessel peak pressure at the bottom of the vessel remains at 1375 psig. The assumed pressure difference of 30 psig still assures compliance with ASME code criteria of 110% of vessel design pressure (i.e.110% x 1250 = 1375 psig).
Ucrding changes in the bases have also been incorporated to clarify that compliance of peak vessel pressure with the ASME criteria also assures compliance of the primary system piping with the USASI criteria for the limiting point (i.e. less than 1410 psig at the lowest point in the recirculation line). These changes were recommended by GE to remove the false implication in the current bases that all points in the primary system must remain less than the ASME criteria for the vessel (1375 psig) and are acceptable.
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4 2.6 Barrier Fuel Demonstration The planned demonstration irradiation of pellet / cladding interaction (PCI)-
resistant BWR fuel involves a large scale (144 bundles) irradiation in Quad Cities Unit 2 starting with Cycle 6.
It is proposed that about half (64) of the bunales would be power ramped, in groups of 16, i.e., one group of 16 would be ramped at the end of each of four successive reactor cycles.
The term " barrier fuel" stems from the use of a 0.003-inch thick, high purity zirconium liner, i.e., barrier which is metallurgically bonded to the Zircaloy-2 structural part of the fuel rod cladding. The dimensions of the fuel rods and the mechanical design of the fuel bundle are the same as the current GE prepressurized 8x8 retrofit bundle (P 8x8 R). A general description of the barrier fuel program including information on the program scope, fuel loading and operation, fuel mechanical design, and safety analyses was presented in a General Electric topical report, NED0-24259 (ref. 5) which was reviewed and approved in October 1980.
In approving NED0-24259 we stated (ref. 9) that the PCI barrier fuel demonstration was licensable, pending the receipt of further information to be submitted by the licensee in a reload analysis.
That information would include (a) a detailed operating plan for the demonstration irradiation, (b) a commitment to perform on-line monitoring of fission product activity and post-irradiation examinations of the demonstration assemblies (consistent with GE recommendations), and (c) an estimate of the PCI failure probability (of the barrier fuel relative to standard fuel) that would coincide with each of the planned power ramps.
The licensee's responses to these conditional items are contained in references 10 and 11. These may be summarized as follows:
1.
Demonstration Irradiation Ocerating Plan and Analyses - When more refined predictions are available (by June 1982), CECO will provide more detailed information on the expected peak local powers and power changes in the fuel that will be power ramped during the End of Cycle j
(E0C) 6 control rod withdrawal test. Those data shall indicate information on both the barrier fuel in the ramp cells (the cells for which the end of cycle power ramps are planned) as well as the adjacent fuel in the buffer regions.
2.
On-Line Monitoring and Post-Irradiation Examinations - CECO will notify NRC Headquarters and the regional office should offgas activity increase during the E0C 6 ramp test to levels significantly in excess of the usual noise and transient behavior.
In addition, provided that outage time is available off critical path, CECO will sip the test cell assemblies as well as any buffer region assemblies that are scheduled for reinsertion for Cycle 7 to. confirm that the cladding is sound even if no failure indications were evident from offgas and coolant monitoring during the EOC 6 ramp test.
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Estimate of Fuel Failure Probability - CECO will provide a comoarison of the fuel failure probability for the planned ramp tests of the i
barrier fuel in the test cells relative to a postulated test with standard fuel in the test cells. That information will be supplied in June 1982 (at about mid-Cycle 6).
We have reviewed the licensee's responses and we believe that the informa-tion and commitments provided by CECO in references 10 and 11 are as detailed as possible at this time and that further definition can wait until mid-cycle when the actual E0C conditions and outage critical path are better known. We agree with CECO that the requested additional information on the items noted above, while related to the ramp tests, is not needed for review and approval of the reload licensing and Beginning of Cycle (B0C) 6 startup authorization. We, therefore, conclude that there is reasonable assurance that the proposed demonstration irradiation will not pose a threat to the public health and safety with regard to normal, steady-state operation of the barrier fuel and that the program is, therefore, acceptable.
3.0 Environmental Considerations We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of environmental impact and pursuant to 10 CFR Section 51.5(d)(4) that an environmental I
impact statement or negative declaration and environmental impact appraisal i
need not be prepared in connection with the issuance of the amendment.
4.0 Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendment does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, the amendment does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the oublic will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regula-tions and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Dated: December 23, 1981 909 e
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References 1.
Letter, Schwartz (Ceco) to Denton (NRC), July 27, 1981 2.
Letter, Rausch (CECO) to Denton (NRC), August 21, 1981 3.
" General Electric BWR Generic Reload Fuel Acplication,"
NEDE-240ll-A-1, July 1979 4.
Letter Engel (GE) to Ippolito (NRC), January 30, 1979 5.
" Barrier Fuel Demonstration Bundle Licensing,"
NED0-24259A, May 1980 6.
Letter, Ippolito (NRC) to Gridley (GE), April 16,1979 and enclosed SER 7.
Letter, Buckholz (GE) to Check (NRC), " Response to NRC Request for Information on ODYN Computer Model," September 5,1980 8.
Letter, Buckholz (GE) to Check (NRC), "0DYN Adjustment Methods for Determination of Operating Limits, January 19, 1981 9.
Letter, Tedesco (NRC) to Engel (GE), November 12, 1980
- 10. Letter, Rausch (CECO) to Eisenhut (NRC), November 4,1981
- 11. Letter, DelGeorge (CECO) to Eisenhut (NRC) December 3,1981
- 12. " Loss-of-Coolant Accident Analysis Report for Dresden Units 2 & 3 and Quad Cities 1 & 2 Nuclear Power Station", Rev.1, April 1979, and subsequent Errata aad Addenda Nos. I thru 6.
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