ML20127N312
| ML20127N312 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 11/24/1992 |
| From: | Link B WISCONSIN ELECTRIC POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20127N316 | List: |
| References | |
| CON-NRC-92-138 VPNPD-92-359, NUDOCS 9212010176 | |
| Download: ML20127N312 (7) | |
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VPNPD-92-359 10 CFR 50.4 l
NRC-92-138 10 CFR 50.90 November 24, 1992 Document Control Desk U.S.
NUCLEAR REGULATORY COMMISSION Mail Station P1-137 Washington, DC 20S55 Gentlemen:
DOCKETS 50-266 AND 50-301-TECHNICAL SPECIFICATIONS CHANGE REOUEST 153 HQDIFICATION OF TECHNICAL SPECIFICATION 15.3.10.A.5 ZERO POWER ROD INSERTION LIMIT POINT BEACH NUCLEAR PLANT. UNITS 1 AND 2 In accordance with the requirements of 10 CFR 50.4 and 50.90, Wisconsin Electric Power Company (Licensee) hereby requests amendments to Facility' Operating ~ Licenses DPR-24 and'DPR-27.
for Point Beach Nuclear Plant, Units 1 and 2 respectively,_to incorporate changes to the plant Technical Specifications.
The proposed revisions _will modify Technical Specification-l Section 15.3.10, " Control Rod and Power Distribution Limits,"
Specification 15.3.10.A.5, specifica'lly removing:the applicability of this section when the reactor is in-hot shutdown.
Marked-up Technical Specification pages with the proposed. changes, a safety evaluation, and the no significant hazards determination are enclosed.
DESCRIPTION OF CURRENT LICENSE CONDITION Specification 15.3.10.A.5 requires that the critical rod position
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not be lower than the-incertion limit for zero power when the reactor is in a hot _ shutdown condition or during any approach.to criticality.
The requirement provides assurance that the reactor will not reach criticality before all the control banks are above their respective insertion limits, ensuring adequate-shutdown margin.
This requirement is notLapplicable when physics testing.is being performed.
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Document Control Dask November 24, 1992 Page 2 DESCRTPTION OF PROPOSED CHANGES This Technical Specification Change Request proposes to modify Specification 15.3.10.A.5 as follows:
"During any approach to criticality, except for physics tests, the critical rod position shall not be lower than the insertion limit for zero power.
That is, if the control rods were withdrawn in normal sequence with no other reactivity change, the reactor would not be critical until the control banks were above the insertion limit."
This change will remove any reference to the hot shutdown condition and make the section only applicable during an approach to criticality.
Shutdown requirements vill continue to be governed by the existing shutdown margin requirements specified in Section 15.3.10.A.3.
BASIS AND JUSTIFICATION Section 15.3.10, " Control Rod and Power Distribution Limits,"
ensures core subcriticality following a reactor trip, limits potential reactivity insertions from a hypothetical rod cluster control assembly ejection, and ensures an acceptable core power distribution during power operation.
The control rod insertion limits are one of the methods used to ensure that these conditions are mat.
Control rod insertion limits provide for achieving bot shutdown by reactor trip at any time during core life, even if the highest worth control rod remains fully withdrawn.
A 10% margin in reactivity wor' h of control rods is used to assure meeting the requirements of the PBNP Final Safety Analysis Report safety analyses.
Inserticn limits also provide a limit on the maximum inserted rod worth in the unlikely event of a hypothetical rod ejection, as well as to ensure that acceptable nuclear peaking factors are maintained.
This change is being proposed in order to accommodate specific plant conditions that could exist immediately following a reactor trip from power.
Immediately following a trip, the existing power defect may be greater than the difference in rod worth between the h
100% power rod insertion limit and the 0% power rod insertion limit.
This would result in the critical rod position being below the zero power rod insertion limit.
This is most likely to occur at the end of core life because the magnitude of the power defect increases throughout core life as a result of U-235 depletion.
The magnitude of the power defect is related to the ratio of U-238 to U-235.
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Document Control Desk November 24, 1992 Page 3 In practice, there is no need to require this section to be applicable when the reactor is in hot shutdown.
The intent of this section is to prevent a critical approach from being performed if the critical rod position is below the 0% power rod insertion limit.
This is required to ensure that sufficient shutdown margin exists prior to a reactor criticality.
Specification 15.3.10.A.5 already requires that the critical rod position be above the 0%
power rod insertion limit before a critical approach can be performed.
Additionally, hot shutdown conditions will still be 4
governed by the requirements of Specification 15.3.10.A.3 which provides requirements for shutdown margin.
It has been determined that the proposed amendments do not involve a significant hazards consideration, authorize a significant change 4
l in the types or total amounts of any effluent release, or result in any significant increase in individual or cumulative occupational exposure.
We therefore conclude that the proposed amendments meet the requirements of 10 CFR 51.22 (c) (9) and that an environmental impact statement or negative declaration end environmental impact appraisal need not be prepared.
In summary, this proposed amendment only removes an unnecessary requirement from Section 15.3.10.A.5 while maintaining the intent of the section.
This change is not safety significant, but it will accommodate acceptable plant conditions that could exist immedi-ately following a reactor trip from power.
Please process this requested change at your earliest convenience.
Please contact us if there are any questions.
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Sincere}y, l
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Bob Link Vice President Nuclear Power l
FDP/jg Enclosures cc:
NRC Regional Administrator NRC Resident Inspector Public Service Commission of Wisconsin i
i Subscribed and sworn before me on this W day of 7 h mf A 1992.
i 0nrubc bMDtki No hrgjPublic, State of Wisconsin My commission expires /c/27/96 I
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IECHNICAL SPECIFICATIONS CHANGE REOUEST 153 SAFETY EVALUATION INTRODUCTION Wisconsin Electric Power Company (Licensee) has applied for amendments to Facility Operating Licenses DPR-24 and DPR-27 for Point Beach Nuclear Plant, Units 1 and 2.
The amendments pronose to modify Technical Specification Section 15.3.10, " Control Rod and Power Distribution Limits," Specification 15.3.10. A.5 by removing the applicability of this specification when the reactor is in hot shutdown.
EVALUATION The intent of Specification 15.3.10.A.5 is to prevent a reactor criticality below the control rod insertion limita.
Control rod insertion limits provide for achieving hot ahutdown following a reactor trip at any time during core life, even if the highest worth control rod remains fully withdrawn.
These requirements additionally provide a limit on the maximum 1 serted rod worth in the unlikely event of a rod ejection, as well as ensure that 3
acceptable nuclear peaking factors are maintained.
Control rod insertion-limits are only applicable during power operation and during an approach to criticality.
When the reactor is being maintained in hot shutdown,-prior to the commencement of a critical approach, the control rod insertion limits are not applicable.
Shutdown margin requirements are maintained in accordance with the requirements of Technical Specification 15.3.10.A.3.
With the reactor in hot shutdown, severai conditions must be met before a critical approach can be commenced.
One of-these-conditions is the performance of an estimated rate position (ERP) calculation.
This calculation is performed to determine a set of conditions which will achieve a criticality giv-n the conditions cf the previous criticality..An ERP calculatioc. is required to be performed after both a planned and unplanned reactor _ trip.
One of the requiremen<r of this calculation is that the minimum rod position obtained for the ERP be at least forty steps above the zero power rod insertion limit.
This ensures that a reactor criticality will only occur above the control rod insertion limits so that sufficient shutdown margin will be present.
This change is being proposed-because it has been determined that a violation of Technical Specifications could occur immediately following a reactor trip from power.
_This violation could result-from a possible condition where the existing power defect would 1
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be larger in magnitude-than the difference in rod worth between the 100% power rod insertion limit and the 0% power rod insertion t
limit.
This would result in the critical rod position being below the zero power rod insertion limit.
The potential for a violation is greatest at the end of core life because the magnitude of the power defect increases throughout core life.
The magnitude of the power defect _ increases over core life as a result of U-235 fuel depletion, effectively increasing the ratio of U-238 to U-235.
I The duration of this condition would only be at long as the amount of time required for the buildup of Xenon to add sufficient e:< cess negative reactivity to the core.
The operators could also borate the Reactor Coolant System to insert the required amount of negative reactivity to ensure that the reactor goes critical at a predetermined rod position.
There is no reduction in nuclear safety, and operator actions would not be i
affected.
l Finally, removing the portion of m 'ation 15.3.10.A.5 that refers
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to the hot shutdown condition wil:
minimize the controls in j
place for this mode of Operation.
shutdown conditions would still be governed by Specification 1 L.3.10.A.3 which considers shutdown margin requirements.
CONCLUSION In summary, this proposed Technical Specification change is administrative in nature and is not safety significant.
Renoving the applicability of this section when the reactor is in hot shutdown will not change either the intent of Specification i
15.3.10.A.5, or the actual operation of Point Beach Nuclear
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Plant.
Additionally, hot shutdown conditions will still be governed by Section 15.3.10.A.3 which considers shutdown margin j
requirements.
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TECHNICAL SPECIFICATION CHANGE REOUEST_151 "No SIGNIFICANT HAZARDS CONSIDERATION In accordance with the requirements of 10 CFR 50.91(a), Wisconsin Electric Power Company (Licensee) has evaluated the proposed changes against the standards of 10 CFR 50.92 and has determined that the operation of Point Beach Nuclear Plant, Units 1 and 2 in accordance with the proposed amendments does not present a significant hazards consideration.
Our analysis against the requirements of 10 CFR 50.92 and the basis for this conclusion follows:
1.
Operation of this facility under the proposed Technical Specification will not create a significant increase in the probability or consequences of an accident previously evaluated.
This proposed change modifies Specification 15.3.10.A.5 by removing I',s applicability when the reactor is in hot shutdown.
The intent of this section is to prevent the occurrence of a reactor criticality below the control rod insertion limits.
Under the proposed amendments, the intent of this section will still be maintained because sufficient actions to enuure that a criticality only occurs above the control rod insertion limits are still required to be performed before a critical i
approach can be commenced.
Additionally, the proposed changes will not minimize the existing controls for the hot shutdown mode of operation.
Specification 15.3.10.A.3 adequately addresses the hot shutdown condition in its consideration of shutdown margin requirements.
There is no physical change to the facility, its systems, or its operatioil.
Thus, an increased probability or consequences of an accident previously evaluated cannot occur.
2.
Operation of this facility under the proposed Technical Specification will not create the possibility of a new or different kind of accident from any accident previously evaluated.
This proposed change modir~ies Specification 15.3.10.A.5 by removing its applicability when the reactor is in hot shutdown.
The intent of this section is to prevent a reactor criticality below the control rod insertion limits.
Under the proposed amendments, the intent of this section will be maintained.
Sufficient actions to ensure that a criticality only occurs above the control rod insertion limita are still required before a critical approach can be commenced.
Additionally, the proposed changes will not minimize the existing controls for the hot shutdown mode of operation.
Specification 15.3.10.A.3 adequately addresses the hot shutdown condition in its consideration of shutdown margin requirements.
There is no physical change to the facility, its systems, or its operation.
Thus, a new or different kind of accident cannot occur.
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l 1-3, operation of this facility under the proposed Technical j
i Specification will not create a significant reduction l
in a margin of safety.
This proposed change modifies Specification 15.3.10.A.5 by_ removing its applicability 1
when the reactor is in hot shutdown.
The intent of this l
section is to prevent a reactor criticality below the control rod insertion limits.
Under the proposed cuend-ments, the intent of this section will be maintained.
Sufficient actions to ensure that a criticality only occurs above the control rod insertion limits are still required i
to be performed-before a critical approach can be commenced.
Additionally, the proposed changes will not minimize the existing controls for the hot shutdown mode of operation.
Specification 15.3.10.A.3 adequately addresses the hot 2
shutdown condition in its consideration of shutdown margin i
requirements.
There is no physicel change to the facility, its systems, or its operation.
Thus, a significant reduction in a margin of safaty cannot occur.
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