ML20126A924
| ML20126A924 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 05/22/1985 |
| From: | PUBLIC SERVICE CO. OF COLORADO |
| To: | |
| Shared Package | |
| ML20126A916 | List: |
| References | |
| FRN-50FR27508 P-85179, NUDOCS 8506130514 | |
| Download: ML20126A924 (8) | |
Text
Attachment 2 to P-85179 Fort St. Vrain #1 Technical Specifications Amendment No.
Page 4.9-l Specification LCO 4.9.3 Xenon Stability Testing l
Limiting Condition for Operation l
The requirements of Specification 4.1.3 and 4.1.4 may be l
suspended during the performance of the Xenon Stability l
physics tests provided power perturbations do not exceed l
those which are expected, as determined by an engineering l
evaluation performed prior to the test, and approved by the l
NFSC.
l APPLICABILITY: During Xenon Stability physics tests.
l ACTION:
I a.
With the occurrence of power perturbations in excess of l
the approved maximum limits, reduce thermal power l
sufficiently to stop power perturbations.
l Surveillance Requirement:
There is no specific surveillance l
requirement associated with LCO 4.9.3.
This test is conducted l
in accordance with the appropriate B series start up test l
procedures, h hK f
P
r P-85179 Fort St. Vrain #1 Technical Specifications Amendment No.
Page 4.9-l Basis for Specification LC0 4.9.3 l
In order for the Xenon Stability characteristics of the l
reactor core to be demonstrated, it is necessary to attempt to l
initiate xenon oscillations by inserting an out of sequence rod.
l The limits on the average temperature rise in LCO 4.1.7, shall l
be maintained throughout this test.
Maintaining. operation l
within these-limits will fully protect plant equipment-and the l
health and safety of the public.
l A detailed engineering evaluation will be performed in l-advance of any Xenon Stability Testing in order to analyze the l
planned test configuration to assure compliance with the intent l
of LCO 4.1.3 and LC0 4.1.4 throughout the test.
This l
engineering evaluation will assure that the maximum worth rod l
pair criteria is met (see FSAR, section 14.2.2.6 and 3.5.5.1),
l and that the assumptions utilized in development of Core Safety l
Limit SL 3.1 (with regards to region, column, and axial peaking l
factors) remain valid throughout the test.
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' 3, ATTACHMENT 3 SIGNIFICANT HAZARDS CONSIDERATIONS
~.
to P-85179 1
SIGNIFICANT HAZARDS CONSIDERATIONS The temporary suspension of the two Technical Specifications does not endanger the health and safety of the public since all other Technical Specifications are in force and all Plant Protective System Trip Settings are unchanged.
Based on the above, operation of Fort St. Vrain in accordance with the proposed changes will not 1) involve a significant increase in the probability or consequences of an accident previously e. valuated,
- 2) create the possibility of a new or different kind of accident from any accident previously evaluated, or 3) involve a significant reduction in a margin of safety.
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ATTACHMENT 4 XENON STABILITY TEST EXCEPTION
SUMMARY
Attachment.4 to P-85179 XENON STABILITY TEST EXCEPTION
SUMMARY
Introduction
- Sequence. 75 of B-0 start-Up Test (Xenon Stability) will be performed during the current refueling cycle at Fort St.
Vrain (FSV). The performance of this test will require the suspension of certain Technical Specifications for the test to yield meaningful results.
The purpose -of 'this test is to show that power perturbations will be dampened by xenon concentration perturbations.
-That is, a section of the core, where the power is high, will, in time, produce higher concentration of xenon.
This test, by inserting an out of sequence rod, will attempt to initiate xenon oscillations. That rod will be withdrawn and power oscillations due to xenon concentration' changes could begin.
It should be noted that each subsequent power shift will be at a reduced magnitude, thus, halting the power perturbations.
Method of Testing To attain the most meaningful results, the Xenon Stability _ Test should be initiated by the partial insertion of a ring.four control rod while at approximately 100% rated thermal power..In order to accomplish this during the current fuel cycle, the temporary suspension of Technical Specifications LC0 4.1.3 and LCO 4.1.4 is required. The suspension is necessary ove to the current rod withdrawal sequence, which requires all ring four control rod groups to be fully withdrawn before reaching 100%
power.
Expected Results The type of power perturbations expected to occur are shown in 1
Figure 1 (attached). This curve is a representation of the type of power perturbations expected to occur during the test. The actual curve will be determined prior to the test, so current core conditions (i.e.,
burn-up, core configuration, and operating history) may be used in calculating the expected power perturbations.
The maximum limits will be defined during the engineering evaluation performed prior to the test. These limits will be based, not on the power oscillations that are expected, but on the prevention of fuel damage.
l
m to P-85179 a:
- 0 Safety Considerations The partial insertion.of an out of sequence rod, required by
- this test, poses no significant safety hazard to.the plant,
- plant. personnel, or the general public. The core will be kept within the limits of LCO 4.1.7, and all Plant Protective System-Trip Settings will remain at their' normal value during the Xenon Stability Test.
- Conclusion Although. the temporary suspension of-two Technical
- Specifications'will be requested under a special test exception,
- no safety limits will be exceeded-nor will any Plant Protective System Trip Points be altered. This will ensure that the health and safety of the pubite will be protected during Sequence'75 of
' B-0 Start-Up Test.
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