ML20100K572
| ML20100K572 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 12/04/1984 |
| From: | Rybak B COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20100K574 | List: |
| References | |
| 9445N, NUDOCS 8412110184 | |
| Download: ML20100K572 (5) | |
Text
,' N Commonwealth Edison e
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) On) First Nahonal Platt. Chicago. Illinois
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7 Address Reply to: Post Offica Box 767
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j Chicago. Illinois 60690 December 4, 1984 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Quad Cities Station Unit 2 Proposed Amendment to the Technical Specifications LHGR Limit During Cycle 7 Barrier Fuel Ramp Test NRC Docket No. 50-265 References (a):
T. J. Rausch letter to H. R. Denton dated January 27, 1983.
(b):
R. B. Bevan letter to D. L. Farrar dated March 3, 1983.
Dear Mr. Denton:
Pursuant to 10 CFR 50.59, Commonwealth Edison herein proposes to amend Appendix A to the Technical Specification of Facility Operating License DPR-30.
The purpose of this proposed amendment is to increase by 12 percent the LHGR limit for Barrier Fuel Assemblies in the Barrier Demonstration Cells from 13.4 kw/ft to 15.0 kw/ft.
The LHGR increase is necessary to properly perform a control rod withdrawal ramp test at the end of Cycle 7.
Currently the test is scheduled for late February, 1985.
A similar request was made during Cycle 6, per Reference (a), and approved by Amendment No. 79, per Reference (b).
Withcut this change there is a strong possibility that the Barrier Fuel Ramp Test will be severely compromised because control rods would have to be reinserted in order not to exceed the current LHGR limits.
Our justification for the increase LHGR for specific barrier fuel bundles is provided in Attachment 1.
This proposed change has received On-Site and Off-Site review and approval, and is submitted in Attachment 2.
We have reviewed this amendment request and find that no l
significant hazards consideration exists.
Our review is documented in Attachment 3.
Commonwealth Edison is notifying the State of Illinois of our request for this amendment by transmittal of a copy of this letter and its attachments to the designated State Official, l
ggl 6
I 8412110184 841204 PDR ADOCK 05000265 P
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H. R. Denton -
December 4, 1984 Your immediate attention to this request is required as Quad Cities Unit 2 is projected to reach the proper test conditions, end of full power reactivity, in late February, 1985.
Pursuant to 10 CFR 170, a fee remittance of $150.00 is enclosed.
Three (3) signed originals and thirty-seven (37) copies of this letter and its attachments is provided for your use.
Very truly yours, ts.
B. Ry Nuclear Licensing Administrator 1m cc:
R. Bevan - NRR NRC Senior Resident Inspector - Quad Cities Attachments (1):
SafetyiEvaluation (2):
Proposed Change to DPR-30 (3):
No Sigr.ificant Hazards Consideration SUBSCRIBED AND SWORN to befcire me this y > 4 day o f j5us c., / 4.. )
, 1984 b:s l, e h. i i+L Notary Public 9445N
9 O
I ATTACHMENT 1 SAFETY EVALUATION FOR INCREASED LINEAR HEAT GENERATION RATE QUAD CITIES 2 CYCLE 7 BARRIER FUEL RAMP TEST
Background
The purpose of this attachment is to provide a technical basis for temporarily increasing the Technical Specification limit on linear heat generation rate (LHGR) from 13.4 kw/ft to 15.0 kw/ft on specified barrier fuel bundles at the end of Cycle 7 (EOC7).
The specific barrier fuel bundles are those located in the demonstration ramp cells.
The ramp demonstration involves control rod withdrawals which will significantly increase the LHGR of the corner fuel rods in the ramped fuel bundles.
The effect on the limiting LHGR transi-ents has been examined for this situation.
This evaluation found that the ramp cell fuel would experience peak LHGRs well below the safety limits specified in Reference 1.
Provided below is a summary of the items addresssed in reaching this conclusion.
The design of the barrier ramp demonstration for E0C7 is predicted to achieve a peak LHGR of 13.4 kw/ft on the ramp cell fuel based on General Electric's 3-dimensional simulator calculations.
This peak LHGR occurs in the wide-wide corner rod of the ramp cell bundles (16 rods).
Monitoring of the actual LHGR's during the demon-stration will be performed by the process computer (P/C) program P-1.
Due to uncertainties in both the 3-D simulator prediction and in the in-core instrumentation and P-1 power solution, the peak LHGR's calculated by P-1 will not agree exactly with the 3-D simulator results.
The LHGR's in the barrier fuel calculated by P-1 during the barrier ramp demonstration may indicate a violation of the Technical Specification limit of 13.4 kw/ft.
We are therefore proposing a relaxation of the Technical Specification limit to allow a temporary increase to 15.0 kw/ft for the maximum allowable LHGR for the barrier fuel during the demonstration and for the duration of Cycle 7 operation subsequent to the test.
This change will allow the entire test to be performed without having to reinsert the control rods to fulfill the Technical Specification action statements if 13.4 kw/ft should be exceeded by a small amount as measured by the P/C.
This request is consistent with that made for the end of Cycle 6 ramp demonstration (Reference 2).
Without this change, there is a possibility that the Barrier Fuel Ramp Test rods will have to be reinserted.
However, it should be noted thct if the P-1 calculated LHGR does exceed the current 13.4 kw/ft Technical Specif1-cation limit, the duration of operation with the calculated value above 13.4 is expected to be less than a month due to local and core-wide fuel depletion as the core passes through the end of full power reactivity.
1 w
^
_. LSince only'the sixteen wide-wide corner = pins-in these four
' ramp cells are expected to reach LHGR values near 13.4 kw/ft, the relaxation,need.only apply to these bundles.
The, Minimum Critical.
Power Ratio-(MCPR) and Maximum Average Planar-Linear. heat Generation
-Rate (MAPLHGR) values are calculated to remain well below the operating limits'during the demonstration and therefore no waiver of
.these'7 11mits-is necessary.
A review of the. limiting LHGR events was performed to-assure.that no violation of licensing safety: limits would occur. LThat is, the peak LHGR during any-normal or abnormal-i transient.(if initiated with a ramp cell rod at 15.0 kw/ft) will be I
less than the LHGR at which 1% plastic strain is calculated to
' occur.
For BP8x8R-fuel (UO2 rods) this corresponds to a LHGR j
value of 23.1 kw/f t. for exposures up to 25,000 MWD /ST (Table 2-3 of'
}.
Reference 1).
The' ramp cell fuel is predicted to have nodal exposures 1n the range of 7000-16000 MWD /ST at the time of the 4
~
demonstration.- The following. sections address specific events.
l l Rod' Withdrawal Error-(RWE)
-The only transient associated with the ramp ~ cell control rod l'
withdrawal'would be if a single ramp cell control rod was' completely removed after a peak pin power of 15.0 kw/f t is achieved.
Assuming.
c
- this inadvertent RWE is initiated at the beginning of the ramp withdrawals, at rated core conditions,fthe maximum core power i.
achieved would be less than 103% 'of ' rated power. :The expected peak
.LHGR for the RWE would'be'less than 15.5 kw/ft.
L Rod Drop Accident (RDA) l The RDA is' initiated with the core in a cold condition, where cold excess reactivity is a maximum for the cycle.
For QC2 C7, the L
RDA was evaluated at the beginning of cycle (80C7).
The RDA at the i
and of-full' power would be less severe than the RDA reported in the reload licensing submittal.
Fuel Loadina Error (FLE)
For the rotated FLE, a 180* misloading would result in the higher enriched narrow-narrow' corner pin being located at the wide-wide corner; The peak LHGR is calculated to be less than 17.1 kw/ft if the unrotated bundle is at 15.0 kw/ft.
Pressurization Transients The worst pressurization transient with respect to peak heat flux based on the results reported in the QC2 Cycle 7 License Supplement.is the Load Rejection Without Bypass.
This transient also yields-the worst peak nodal heat flux of 122% of the initial heat' flux.
Assuming the ramp cell fuel is on limits at the start of this event the resulting peak LHGR would be 18.3 kw/ft.
m
'.s 4
1
- 3-Cold Water Events
-The worst cold, water event with respect-to peak heat flux reported in the Licensing' Supplement -is the Loss of Feedwater-Heaters.
This results in a peak heat flux. of.120% of the initial
. heat. flux.. Assuming the ramp. cell fuel is on limits at the start of this event, the resulting peak-LHGR would be-18.0 kw/ft.
'ECCS Considerations General Electric has evaluated th' effects of the special bundle e
enrichments on the ECCS analysis and has determined that observance of:the current MAPLHGR technical specification limits for these.
demonstration bundles (even with corner rod operating at 15.0 kw/ft)'
> ensures compliance with the 10 CFR 50 Appendix K limits.
Stability Considerations Stability is of concern at low flow and high radial peaking.
.The' ramp demonstration will occur at or near full flow and with a less than design radial peaking factor.
The core-wide response remains the same as that used in the licensing analyses.
Therefore, j.
the current core stability anal
. Technical Specification waiver.ysis is applicable for the proposed l.
Conclusion Based on the above evaluation, it can be concluded that increasing the Technical Specification value of LHGR from 13.4 to 15.0 kw/ft is really an administrative change to preserve the-margin typically maintained between the process computer and design methods.. Evaluation results show that the expected LHGR will not exceed 13;4 kw/ft and that if.it did reach 15.0 kw/ft none of the
. previously established safety" limits,would be e'xceeded.
Thus, a temporary change inithe Technical Specification LHGR limit for this specific. event is reasonable and technically justified within all L
safety. criteria, m
l-
- References
' General Electric Standard Application for Reactor Fuel,"
1.
'NEDE-240ll-P-A-6.
2.
" Quad Cities Station Unit 2, Proposed Amendment to Operating j
' Licensing DPR-30 concerning the LHGR Limit during the Cycle 6 l
Barrier Dual Ramp Test," NRC Docket No. 50-265, Transmittal of f
T. J. Rausch to'H.R. Denton, January 27,.1983.
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