ML20077L418
| ML20077L418 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/29/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20077L406 | List: |
| References | |
| NUDOCS 9501110334 | |
| Download: ML20077L418 (4) | |
Text
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UNITED STATES y'
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NUCLEAR REGULATORY CDMMISSION WASHINGTON, D.C. 200064001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 99 TO FACILITY OPERATING LICENSE NO. NPF-49 NORTHEAST NUCLEAR ENERGY COMPANY. ET AL.
MILLSTONE NUCLEAR POWER STATION. UNIT NO. 3 DOCKET NO. 50-423
1.0 INTRODUCTION
By letter dated July 22, 1994 the Northeast Nuclear Energy Company (the licensee) submitted a request for changes to the Millstone Nuclear Power Station, Unit No. 3 Technical Specifications (TS). The requested changes would make three separate changes: (1) change the title of Figure 3.1-5 to be consistent with the applicable Limiting Condition For Operation (LCO), (2) relocate the Chemical and Volume Control System (CVCS) valve position i
requirements to the Reactivity Control Systems - Shutdown Margin specifications, and (3) consolidate action statements to be expressed in the LCOs rather than in Surveillance Requirements (SR).
The amendment would also clarify the requirements for calculating the heat flux hot channel factor F,(z) when using the base load option.
2.0 BACKGR0VND 2.1 Power Distribution Limits I
The licensee proposed TS changes that pertain to power distribution limits and the heat flux hot channel factor (Fe(Z)).
In order to separate applicable actions from SRs and place them in action statements, the licensee proposed changes to TS 3.2.2.1.
Currently, the specified actions conflict with the designated LCO actions.
The purpose of the limits on the values of Fe(Z) is to limit the local (i.e., pellet) peak power density. The value of Fo(Z) varies along the axial height (Z) of the core.
Fe(Z) is defined as the maximum local fuel rod linear power density divided by the average fuel rod linear power density, assuming nominal fuel pellet and fuel rod dimensions. Therefore, Fo(Z) is a measure of the peak fuel pellet power within the reactor core.
9501110334 941229 DR ADOCK 050004 3
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< During power operation, the global power distribution is limited by LC0 3.2.1,
" AXIAL FLUX DIFFERENCE (AFD)," and LCO 3.2.4, " QUADRANT POWER TILT RATIO (QPTR)," which are directly and continuously measured process variables.
Therefore, these LCOs preserve core limits on a continuous basis.
Fe(Z) varies with fuel loading patterns, contrcl bank insertion, fuel burnup, and changes in axial power' distribution.
Fe(Z) i: c:casured periodically using the incore detector system. These measurements are generally taken with the core at or near steady state conditions. Using the measured three dimensional power distributions, it is possible to derive a measured value for Fe(Z).
However, because this value represents a steady state condition, it does not include the variations in the value of Fe(Z) that are present during nonequilibrium situations such as load following.
The steady state value of the fundamental radial peaking factor (F,y) is adjusted by an elevation dependent factor to account for the variations in Fe(Z) due to transient conditions. Core monitoring and control under nonsteady state conditions are accomplished by operating the core within the limits of the appropriate LCOs, including the limits on AFD, QPTR, and control rod insertion.
2.2 Editorial and Administrative Chanaes The licensee identified certain typographical errors and subsequently provided corrected pages during the November 2, 1994 meeting with the NRC staff regarding instrument surveillance. The affected pages are 3/4 2-6, 3/4 2-7, 3/4 2-13, and 3/4 2-14.
The content of these pages and the changes made neither expand the scope of the July 22, 1994 amendment request nor affect the i
initial proposed no significant hazards consideration determination.
2.2.1 Title Chanae of Fiaure 3.1-5 The licensee proposed to change the title of Figure 3.1-5, " Required Shutdown Margin for Mode 5 with RCS Loops Drained." The LC0 in Section 3.1.1.2 applies to " loops not filled" and refers the reader to Figure 3.1.1.2.
In order to establish continuity between the two items, the words " loops drained" in the title of Figure 3.1-5 are being changed to " loops not filled" as specified in its associated LC0 in Section 3.1.1.2.
2.2.2 Relocation of CVCS Position Reauirements The licensee requested that several administrative changes be made to the TS regarding CVCS valve position requirements for reactivity control during cold shut down and refueling operations. The proposed change would allow the CVCS valve position requirements stated in Section 3.4.1.4.2 to be relocated in Section 3.1.1.2, " Reactivity Control Systems - Shutdown Margin - Cold Shutdown
- Loops Not Filled".
In doing so, 3.1.1.2 will include an additional action statement that explains the actions to be taken when the CVCS dilution flow paths are not closed and locked into position.
Subsequently, SR 4.4.1.4.2.3 will be moved to SR 4.1.1.2.2 to address the surveillance procedures for the l
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associated CVCS valves.
Finally, TS 3/4.9.1.1 will be modified to refer. to Section 4.1.1.2.2 that will contain the CVCS valve position requirements.
3.0 EVALUATION 3.1 Heat Flux Hot Channel Factor (TS 3.2.2.1)
TS 3.2.2.1.a.2, which requires reducing thermal power by 2 1% for each 1% by which Fe(Z) exceeds its limit, maintains an acceptable absolute power density.
The completion time of 15 minutes provides an acceptable time to reduce power in an orderly manner and without allowing the plant to remain in an unacceptable condition for an extended period of time.
l The bases for TS 3.2.2.1.a.1 are as follows. When core peaking factors are sufficiently high such that LCO 3.2.1 does not permit operation at Rated Thermal Power (RTP), the acceptable operation limits for AFD are scaled down.
1 This percentage reduction is equal to the amount, expressed as a percentage, by which Fe(Z) exceeds its specified limit. This ensures a near constant maximum linear heat rate in units of kilowatts per foot at the acceptable operation limits. The Completion Time of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for the change in setpoints is sufficient, considering the small likelihood of a severe transient in this relatively short time period, and the preceding prompt reduction in thermal i
power in accordance with Required Action 3.2.2.1.a.2.
A reduction of the Power Range Neutron-High trip setpoints by 21% for each 1% by which Fe(Z) exceeds its specified limit, is a conservative action for protection against the consequences of severe transients with unanalyzed power distributions. The completion time of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is sufficient ',onsidering the small likelihood of a severe transient in this time period and the preceding prompt reduction in thermal power in accordance with Required Action Statement 3.2.2.1.a.2.
Reduction in the Over>ower AT trip setpoints by 2 1% for each 1% by which f
Fe(Z) exceeds its lim' t, is a conservative action for protection against the consequences cf severe transients with unanalyzed power distributions. The completion time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is sufficient considering the small li h11 hood of a severe transient in this time period, and the preceding prompt reduction in i
thermal power in accordance with Required Action Statem nt 3.2.2.1.a.2.
I Verification that Fe(Z) has been restored to within its limit, by performing i
SR 3.2.1.1 prior to increasing thermal power above the li.?.it imposed by Required Action Statement 3.2.2.1.a.2, ensures that core conditions during operation at higher power levels are consistent with safety analyses assumptions.
If Required Actions 3.2.2.1.a.1 through 3.2.2.1.a.3 are not met within their associated completion times, the plant must be placed in a mode or condition in which the LCO requirements are not applicable. This is done by placing the plant in at least MODE 2 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. This allowed Completion Time is reasonable based on operating experience regarding the amount of time it takes i
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to reach MODE 2 from full power operation in an orderly manner and without challenging plant systems.
3.2 Editorial and Administrative Chanaes The administrative changes do not alter the operation of the plant, and are I
further clarifications of the existing TS requirements. Based on the foregoing' discussion, the NRC staff finds the proposed amendment changes acceptable.
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4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Connecticut State official was notified of the proposed issuance of the amendment. The State official had no comments.
5.0 ENVIR m The amendment changes a requirement with respect to installation or use of a l
facility component located within the restricted area as defined in 10 CFR i
Part 20 and changes surveillance requirements. The NRC staff has determined l
that the amendment involves no significant increase in the amounts, and no 5
significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative t
occupational radiation exposur. The Commission has previously issued a i
proposed finding that the amendment involves no significant hazards i
consideration, and there has been no public comment on such finding (59 FR i
45029). Accordingly, the amendment meets the eligibility criteria for i
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.
6.0 CONCLUSION
l The Commission has concluded, based on the considerations discussed above, I
that:
(1) there is reasonable assurance that the health and safety of the
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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 i
defense and security or to the health and safety of the public.
Principal Contributor: Maudette Griggs Date:
December 29, 1994 e
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