ML20113G360
| ML20113G360 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 01/17/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20113G336 | List: |
| References | |
| NUDOCS 8501240328 | |
| Download: ML20113G360 (6) | |
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o,j UNITED STATES NUCLEAR REGULATORY COMMISSION
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WASHINGTON, D. C. 20655
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I SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION
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SUPPORTIFG AVENDMENT NO. 84 TO PROVISIONAL OPERATING LICENSE NO. DPR-19 COMMONWEALTH EDISON COMPANY DRESDEN NUCLEAR POWER STATION, UNIT NO. 2 DOCKET NO. 50-237
1.0 INTRODUCTION
By letters dated September 11, 27 and 28, 1984 and October 2,1984 (References 1-4), Coninonwealth Edison Company (CECO) (the licensee) proposed to amend Apperdix A of Provisional Operating License No. DPR-19. The letters furnished _information to support authorization for Dresden 2 to operate I
during_ Cycle 10 with reload fuel supplied by and the associated analyses perfonned by Exxon Nuclear Comp'any and to allow for the use of hafnium as a l
' control rod absorber material.
For Cycle 10, the licensee plans to use General Electric (GE) hybrid design hafniu'm control rod. blades in Dresden
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The letters also provided information to support new limiting conditions
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for operation and surveillance requirements for a newly modified scram l
system having improved reliability and changes in the calibration and functional test frequencies for certain specific instruments that are >
i being modified into analog trip systems.
i' Specifically related to the reload fuel, the licensee requested extension of-the maximum averace planar linear heat generation rate (MAPLHGR) curves for 8 x 8 and 9 x 9 (Lead Test Assembly) (LTA) fuel types and for GE P8DRB265H
. fuel type and deletion of the MAPLHGR curve for GE fuel type P80RB239 which has never been used at Dresden and is not expected to be in the future.
I Notices of Consideration of Issuance of Amendment to License and Proposed i
No Significant Hazards Consideration Determination and Opportunity for Hearing related to the requested actions in the aforementioned letters were published in the Federal Register on October 24,198'4(49FRa2815) and November 21, 1984 (49 FR 45944.and 45945). No request for hearing and no consnents were received.
2.0 EVALUATION OF THE PROPOSEC EXTENSION OF'THE BURNUP RANGE FOR FAPLHGR CURVES-DURING D2 CYCLE 10
2.1 Background
Currently the PAPLHGR Technical Specifications for Exxon 8 x 8 and 9 x 9 LTA fuel assemblies extend only to a burnup of 13,500 MWD /FTU.
During Cycle 10 both cf these fuel types are expected to exceed that limit.
8501240328 850117 PDR ADOCK 05000237 P
The licensee is also p'roposing to change the GE P8DRB265H fuel type burn-up limit of the MAPLHGR curve to 45,000 MWD /ST. Although this fuel type is not expected to reach this burnup during Cycle 10, the licensee is proposing a change now to preclude a separate submittal and NRC review at a later date.
2.2 Evaluation The staff has reviewed not only the proposed changes to the MAPLHGR curves themselves.but the other aspects of fuel safety which will be affected by the proposed increase in burnup.
The staff is currently reviewing extended burnup topical reports for both GE and Exxon (References 5 and 6). The review of these reports served as the basis for the extension in burnup proposed by the licensee.
Although the review of these reports is not yet complete, the review has progressed to the point where the staff.can find an acceptable basis for the burnup extension proposed by the licensee. Only one significant issue was found to affect the proposed burnup extension.
This was the selection of a power history;for the calculation to demonstrate that the fuel rod internal pressure'. remains less than the reactor coolant system pressure for the ' Exxon fuel. Since generic discussions are continuing wfth1 Exxon.as part of the review of Reference 6, the staff perfonned an acceptable, independent fuel rod pressure calculation (with the assistance of Battelle Pacific Northwest Laboratories) and determined that the internal pressure of the Exxon fuel rods will not exceed the reactor coolant systam pressure in Dresden 2.
In order to determine the PAPLHGR limits, approved calculational methods were used by the licensee for both the Exxon and GE fuel assemblies (References 7 through 10).
For the Exxon 9 x 9 LTAs, the licensee nhtained the MAPLHGR curve from the Exxon 8 x 8 fuel assemblies by conserving the allowable nodal powers and ratioing the active fuel lengths. This method was used to generate the MAPLHGR curves currently in the Dresden 2 Technical Specifications for these 9 x 9 LTAs. Since it is not obvious that this method is conservative, the licensee performed several loss-of-coolant accident (LOCA) heatup calculations to demonstrate that the peak clad temperature of these 9 x 9 LTAs would remain below the LOCA criteria of 10 CFR 50.46 for'the existing MAPLHGR curves (Reference 11).
Since the stored energy is highest between zero and 13,500 MWD /MTU these calculations are sufficient to cover the longer time period. The GE fuel assemblies'have already l
been approved for operation to 40,000 MWD /ST.
The licensee is proposing an extension to 45,000 MWD /ST.
The steff~ finds this acceptable since the staff has generically approved an extension in burnup for this i
i fuel type to 50,000 MWD /ST in GESTA.R-II (Reference 12) as long as approved l
methods are used for the LOCA analysis, es is the case for this proposed charge to the Technical Specifications.
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2.3 Summary Based on the analysis above, the staff has concluded that the requested extension ~s of the MAPLHGR curves are acceptable. This'is based on the following considerations:
1.
The staff independently determined that the internal pressure of the Exxon. fuel. rods will not exceed the re~ actor coolant system pressure during D2 Cycle 10.
2.
Calculational ~ methods approved by the staff were used to determine the MAPLHGR limits requested by the licensee.
3.0 USE OF HAFNIUM AS A CONTROL ROD ABSORBER MATERIAL FOR DRESDEN 2
3.1 Background
At present, the Dresden 2 Technical Specifications permit only B,C to be used as control rod. absorber material although the use of botn B,C and hafnium has been approved for use in Dresden 3 (Reference 13).
THe licensee's.0ctober 2,'1984 letter requested that hafnium also be pemitted for control rod absorber material in Dresden 2 and proposed i
.that GE type Hybrid I Control Rod (GE Type I HICR) assemblies ~which i
were discussed in the GE Topical Report NEDE-22290-A (Safety Evaluation of the General Electric Hybrid I Control Rod Assembly, September 1983, GE proprietary) be installed.
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3.2 Evaluation and Conclusion
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The staff has previously approved, on a plant-specific basis, the use of hafnium as a control rod absorber material in ASEA-ATOM. control rods inserted in Dresden 3 (Reference 13). While CECO is proposing that the GE Type I HICR assemblies be installed in Dresden 2 during this outage, the amendment request is for the general use of hafnium as a control rod absorber material.
As indicated above, its use in
' ASEA-ATOM blades has been approved by the staff for use in 'its identical sister unit, Dresden 3, and its use in. the GE Type I HICR assemblies
' described in GE Topical Report NEDE-22290-A has been reviewed and approved by the staff in a Safety Evaluation letter ' dated August 22, 1983. Both control rod designs have the same worth and weight as the existing blades. The differe'nces in design are in the cladding and absorber material and serve to improve blade lifetime.
The staff, therefore, concludes that the use of hafnium in control rod blades for Dresden 2 is acceptable providing that the previously approved designs are installed.
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4.0 SCRAM DISCHARGE SYSTEM A Generic Safety Evaluation for the modified scram discharge system, issued December 10, 1980, endorsed the criteria set forth by the BWR Owners subgroup to meet the concerns arising from the Browns Ferry incomplete : cram event of July 1980.
By the NRC Confirmatory Order of June 24, 1982, the licensee's comitment to modify its scram discharge system in response to these concerns was confirmed (Reference 14). Also, model Technical Specifications were forwarded to the licensee as guidance for revising the Technical Specifications for operation with the newly modified scram discharge system.
Following a period of discussion with the licensee regarding the application of the model Technical Specifications to the unit-specific Technical Specifications for the Dresden Nuclear Power Station, the licensee, by letter dated September 27, 1984, proposed Technical Specifications for the newly modified scram discharge system for Unit 2.
The Technical Specification changes proposed i
in the licensee's submittal are fully responsive to the concerns addressed l
in.the Generic Safety Evaluation on Scram Discharge Systems and are in keeping with the guidance provided in the model Technical' Specifications.
Therefore, the staff finds the proposed changes acceptable.
5.0 ANALOG TRIP INSTRUMENT SURVEILf ANCE FREOUENCY Certairf'e'quipment is being replaced to satisfy the requirement of 10 CFR 50.49 a
regarding environmental qualification of electrical equiptrent important to
-safety.
In association with these changes, several existing instruments will be converted into analog trip systems; these are:
Reactor Low Water Level Instrument, 2-263-57AandBand2-263-5EAandB Reactor Water High Level Instrument, 2-263-73A and B HPCI High Steam Flow Instrument, 2-2389A thru D
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HPCI Steam Line Low Pressure Instrument, 2-2352 and 2353 l
The analog trip systems consist of an analog sensor and transmitter, and I
a trip unit arrangement which ultimately actuates a trip relay. The frequency of calibration and functional testing for instrument loops of the analog trip system has been estab.lished in Reference 15, an NRC-approved reference document. With the currently installed one-out-of-two, taken i
twice logic, the prescribed calibration / functional test frequency for the respective transmitters, however, is once per operating cycle. The Technical Specification changes proposed in Reference 3 would require the channel calibration to be performed at the transmitter at a freouency of once per operating cycle.
Since this is the calibration frequency recommended,in the NRC-approved GE Topical Report, NEDO-21617-A (Reference 15), and the proposal is to conform the surveillance requirements to' the recomended and NRC-approved period, the licensee's proposal is acceptable.
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6.0 ENVIRONMENTAL CONSIDERATION
The amendment involves a chan'ge in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements. The staff ha's 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.
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 be prepared in connection with the issuance of the amendment.
7.0 CONCLUSION
S The staff 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, and (2) such activities will be conducted in compliance with the Commission's regulations 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.
8.0 ACKNOWLEDGEMENT
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The following staff members have contributed to this evaluation:
A. Gill and R. Gilbert.
Dited:
January 17, 1985 1
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REFERENCES 1.
Letter, B. Rybak (CECO) to'H. Denton (NRC), dated September 11, 1984 2.
Letter, B. Rybak (CECO) to H. Denton (NRC), dated September 27, 1984.
3.
Letter, B. Rybak (CECO) to H. Denton (NRC), dated September 28, 1984.
4.
Letter, B. Rybak~(CECO) to H. Denton (NRC), dated October 2, 1984.
5.
NEDE-22148-P, Class III, Extended Burnup Evaluation Methodology, June 1982.
(Proprietary) 6.
XN-NF-82-06-P, Rev.1, Qualification of Exxon Nuclear Fuel For Extended Burnup, June 1982.
(Proprietary) 7.
J. E. Krajicek, " Generic Jet Pump BWR3 LOCA-ECCS Analysis Using the ENC EXEM Evaluation Model," XN-NF-81-71(A), November 1981.
8.
D. R. Swope, "Dresden Unit 3 Revised MAPLHGR Anal'ys.is Using the ENC EXEM Evaluation Model," XN-NF-81-75, Supplement 1, July 1983.
9.
J. C. Chandler, "Dresden Unit i. Cycle 10 Reload Analysis," XN-NF-84-46, June 19,84
- 10. NED0-24146A, " Loss-of-Coolant Accident Analysis Report for Dresden Units 2, 3 and Quad Cities Units 1, 2 Nuclear Power Stations," Revision 1. April 1979
.as subsequently modified by Errata and Addenda 1 through 12.
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Letter, T. J. Rausch (CECO) to H. R. Denton (NRC), "Dresden'2 Proposed Amendment to Appendix A Technical Specifications to Support Operation with Fuel Supplied by Exxon Nuclear Company," dated December 21, 1982.
- 12. General Electric Standard Application for Reactor Fuel, GESTAR II, Section 5.2.5.2.5, NEDE-24011 (Ref. 5) Supplement for the United States, August 1982.
(Proprietary)
- 13. Letter, D. Crutchfield (NRC) to D. Farrar (CECO), " Technical Specification Changes Relating to the Cycle 9 Reload for Dresden Nuclear Power Station, Unit No. 3, dated March 9, 1984.
- 14. Letter, D. Eisenhut (NRC) to D. Farrar (CECO), dated June 24, 1982.
- 15. GE Topical Report, NEDO-21617-A, " Analog Transmitter / Trip Unit Systems for Engineered Safeguard Sensor Trip Inputs," December 1978.
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