ML17284A481
| ML17284A481 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 08/05/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17284A480 | List: |
| References | |
| NUDOCS 8808190187 | |
| Download: ML17284A481 (11) | |
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UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT N0.62 TO FACILITY OPERATING LICENSE NO. NPF-21 WASHINGTON PUBLIC POWER SUPPLY SYSTEM WPPSS NUCLEAR PROI3ECT N0.2 DOCKET NO. 50-397
1.0 INTRODUCTION
By letter dated March 7, 1988 (G02-88-053) and supplement dated May 13, 1988 (G02-88-116) the Washington Public Power Supply System proposed certain changes to the Technical Specifications for WNP-2.
(The license submitted a letter, dated April 12, 1988, containing corrections to the March 7, 1988 letter.)
The objective of the proposed amendment is to allow the operation of WNP-2 up to a power level of 75K with one recirculation loop operating to the design burnup of the reload fuel of 35,000 MWD/MT bundle average.
The current technical specifications limit the operation to a power level of 72K with one recirculation loop operating, and further, prohibit single loop operation beyond a fuel burnup of 15,000 MWD/MT bundle
- average, On the same date the licensee filed an amendment application and supporting documentation for the license conditions applicable during the fourth fuel cycle of operation (Ref. 1).
The fuel burnup and power level limitations on single loop operation in the current technical specifications are the bounds of the analyses of single loop operation previously submitted by the licensee and reviewed by the staff.
The licensee submitted three reports (Refs 2, 3 and 4) containing additional safety analyses in support of the March 7, 1988 amendment application.
Sections 2.2.1, 3/4.2.1, 3/4.2.2, 3/4.2.3, 3/4.3.6, 3/4.4.1 and associated bases for these sections are proposed to be revised to incorporate new limits for single loop operation.
The licensee also proposed reorganization of one section of the technical specifictions.
Currently Section 3/4.3.10, "Neutron Flux Monitoring Instru-mentation," contains a limiting condition of operation for APRM and LPRM neutron flux noise levels.
The licensee argues that this is not an instrumentation issue and has proposed to move this requirement to section 3/4.2, "Power Distribution Limits."
The licensee also noted that the action statement of existing technical specification 3/4.3.10 did not have a
corresponding LCO to get into the action statement.
To correct this the licensee proposed adding a technical specification addressing flow/power ins tab i 1 ity.
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By letter dated May 13, 1988 (G02-88-116) the licensee clarified that although the peak bundle burnup limits extend to 35,000 MWD/MT the dis-charged fuel will conform to the assumptions of 10 CFR 51.52.
A separate license amendment application (Ref. 1) for Cycle 4 fuel reloading was based on a more conservative analysis which would allow the licensee to refuel in the future without needing further license amendments.
The staff reviewed and approved that application and issued its safety evaluation as part of Amendment 59 to License No. NPF-21.
That application included more conservative MCPR operating limits (Table 3.2.3-1) for single loop operation.
However those proposed single loop limits were not included in the revisions issued with Amendment 59 because the review of this current application for single loop operation had not been completed.
The more conservative single loop MCPR limits requested for the Cycle 4 reload are included in Table 3.2.3-1 at this time.
- 2. 0 EVALUATION 2.1 Sin le Loo 0 eration WNP-2 is currently permitted to operate with one recirculation loop out-of-service at power levels up to 72K of rated power and for burnups up to 15,000 MWD/MTU on the ANF reload fuel.
The initial core GE fuel is permitted to operate to burnups of 44,000 MWD/MTU with single loop operation (SLO).
ANF has performed analyses to evaluate operation of WNP-2 during SLO at power levels up to 75K power and for burnups up to 35,000 MWD/MTU on the ANF reload fuel (Refs. 2, 3).
These analyses were performed for the most limiting transients and accidents and for the LOCA at the maximum extended power state during SLO using approved methodology.
Consideration of the higher uncertainties for core flow, radial power and axial power during SLO results in an increase in the MCPR safety limit of 0.01 (to 1.07), the same value supported by the GE analyses for the initial core GE fuel with a single recirculation loop in operation.
However, the two loop MCPR limits at SLO flow conditions bound the required MCPR limits for SLO conditions including the higher safety limit MCPR.
The results of the ANF analyses support the use of a single bounding MCPR operating limit of 1.35 and two loop ANF fuel MAPLHGR limits for SLO for current and future cycles.
The only exception to this is, in the event the two loop CRWE event operating limit exceeds the current value of 1.26, the single loop CRWE results should be reviewed to ensure they remain conservative.
The licensee has committed to this review (Ref 4).
For GE fuel, the reduction of the MAPLHGR limit to a value of 0.84 times the two recir cu-lation loop operation limit still remains.
The staff finds the proposed conditions for SLO acceptable.
WNP-2 will be entering its fourth cycle of operation and is approaching an equilibrium cycle.
Analysis results between Cycles 3 and 4 show little change.
As a result, WNP-2 has chosen to add some small CPR penalties for margin to envelope future anticipated analysis results (Ref. 5).
The intent is to be able to submit future reload applications which require no Technical Specification
- changes, thereby allowing application per the
provisions of 10 CFR 50.59.
Including these self-imposed penalties for single loop operation increases the MCPR operating limit for GE fuel to 1.40 and for ANF fuel to 1.37.
The staff reviewed these more conservative limits as part of its review of the application for Cycle 4 fuel reloading and found the limits acceptable.
2.2 Reor anization of Technical S ecifications Specification 3/4.3.10 Neutron Flux Monitoring Instrumentation states that the APRM and LPRM neutron flux noise levels shall not exceed three times their established baseline values when operating in the allowable region of Figure 3.3.10-1.
The action statement prescribes steps the licensee must take when the neutron noise flux noise levels do not meet the limiting condition for operation.
The action statement further prescribes steps the licensee must take when reactor power and core flow fall outside of the allowable region of the figure.
The licensee contends that this LCO and associated action statements constitute power distribution limits rather than instrumentation limits. It is proposed to move this to part 3.4.2 of the technical specifications and-to include an LCO corre-sponding to each of the two parts of the action statement.
The staff finds that since the limits are not changed there is no safety significance to this revision and it is, therefore, acceptable.
2.3 Technical S ecification Chan es To accomplish the proposed changes for SLO limits, incorporation of a-modified power/flow operating map, nuclear limits, and Bases and reference
- updates, the following Technical Specification changes have been requested:
(I)
Specification 2.2.1:
The APRf< flow biased simulated thermal power (high) trip setpoint and allowable value for SLO have been removed from Table 2.2.1-1.
This is acceptable because the two loop limits at SLO flow conditions have been shown to bound the required.limits for SLO conditions and no distribution need be made in the reactor protection system instrumentation setpoints.
(2)
Specification 3/4.2.1:
Figure 3.2.1-3 has been revised to include SLO.
These MAPLHGR limits are not impacted by the small enrichment change associated with ANF fuel loaded for Cycle 4.
In addition, for SLO these limits also apply to ANF fuel consistent with the flow dependent MCPR curve (1.35 at 50K of rated flow).
The change is, therefore, acceptable.
(3)
Specification 3/4.2.2:
Separate values of the APRM flow biased simulated thermal power-upscale scram trip setpoint and flow biased neutron flux-upscale control rod block trip setpoint for SLO have been removed.
This is acceptable for the same reasons as stated in (1) above.
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Specification 3/4.2.3:
Table 3.2.3-1 and Figure 3.2.3-1 have been revised to reflect Cycle 4 MCPR operating limits.
These new limits are based on the Cycle 4 reload safety analysis which has been evaluated and approved in Section 2 and are, therefore, acceptable.
Specification 3/4.2.6:
A new Section on Power/Flow Instability has been added.
This was done to clarify the intent of action statement in existing technical specification 3.3.10.
The power/flow operating map which was part of figure 3.3.10-1 is now Figure 3.2.6-1 and has been modified to bound future stability calculations.
Based on the staff's evaluation of the stability analyses and surveillance requirements for Cycle 4, the proposed changes are acceptable.
Specification 3/4.2.7:
A new Section on Neutron Flux Noise Monitoring has been created by moving existing requirements from Section 3/4.3.10.
This provides assurance that neutron flux limit cycle osci llations will be detected and suppressed by monitoring APRM and LPRM neutron flux noise levels while operating in this region and is, therefore, acceptable.
The associated changes to the wording in the LCO and Applicability sections, the Action section, and the Surveillance Requirements are also acceptable.
Specification 3/4.3.6:
The RBM and APRM instrumentation trip setpoints for two loop operation and SLO have been combined.
As stated earlier, this is acceptable.
Specification 3/4.3. 10:
This specification has been relocated to the Power Distribution Limits section of the Technical Specifications as described in item (6) above.
Since the intent of this LCO is to monitor neutron flux noise levels to detect the approach of an unstable region of operation and has little to do with instrument calibration, it is more appropriately located in the Power Distri-bution Limits section immediately adjacent to related LCO 3/4.2.6, Power/Flow Stability.
The relocation is, therefore, acceptable.
Specification 3/4.4.1:
Actions required to be initiated within 15 minutes have been removed from within the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> criteria and local-ized.
The Action requirement to reduce the scram and rod block trip setpoints when in SLO is no longer necessary since the Cycle 4 analysis evelopes operation up to 75K thermal power with single loop core flows and drive flows.
In addition, the reduction in MAPLHGR limit during SLO is changed to only be necessary for the GE fuel as mentioned in Section 2.7.
These changes are consistent with the Cycle 4 reload analysis and are acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
Pursuant to 10 CFR 51.21, the NRC prepared an environmental assessment.
A notice of environmental assessment and finding of no significant impact was published in the Federal
~Re ister on August 2, 1988 (53 FR 29092).
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4.0 CONTACT WITH STATE OFFICIAL T e State of Washington was provided a copy of the amendment application and did not have any covalent.
5.0 CONCLUSION
The staff has reviewed the reports submitted for single loop operation using ANF methodology and analysis.
Based on this review, the staff concludes that the safety of operating with a single recirculation loop out of service for an extended period of time has been adequately demon-strated.
The Technical Specification changes submitted reflect the use of of acceptable methodology and the operating limits associated with those changes.
The proposed operation of WNP-2 is therefore, acceptable.
We have 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 (3) the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
Laurence I. Kopp Dated:
August 5, 1988
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REFERENCES 1.
Letter from G.
C. Sorensen (MPPSS) to NRC, Request for Amendment to Technical Specifications - Reload License Amendment (Cycle 4),
March 7, 1988 (G02-88-054).
2.
ANF-87-119, "WNP-2 Single Loop Operation Analysis," September 1987.
3.
ANF-87-118, "WNP-2 LOCA Analysis for Single Loop Operation,"
September 1987.
4.
WPPSS-EANF-115, "WNP-2 Single Loop Operation Summary Report,"
February 1988.
5.
WPPSS-EANF-119, "WNP-2 Cycle 4 Reload Summary Report," February 1988.
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