ML20214N010
| ML20214N010 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 11/25/1986 |
| From: | Randazza J Maine Yankee |
| To: | NRC OFFICE OF ADMINISTRATION (ADM), Office of Nuclear Reactor Regulation |
| References | |
| MN-86-147, NUDOCS 8612030509 | |
| Download: ML20214N010 (7) | |
Text
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EDISON DRIVE MAME HARHEE ATOMICP0MIERCOMPARUe auOus,s. us,na o<32s (207) 623-3521 November 25, 1986 MN-86-147 Proposed Change 125 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C.
20555 Attention: Document Control Desk
References:
(a)
License No. DPR-36 (Docket No. 50-309)
(b) USNRC Letter to MYAPCo dated June 16, 1982. Safety Evaluation and Environmental Impact Appraisal Regarding Maine Yankee Spent Fuel Storage.
(c) USNRC Letter to MYAPCo dated October 29, 1982, Amendment No. 66 to Maine Yankee Operating License and Supporting Safety Evaluation
Subject:
Technical Specification Proposed Change 125:
Fuel Enrichment Limit Gentlemen:
Maine Yankee Atomic Power Company requests, with this submittal, to amend its Technical Specification (TS) pertaining to the fuel enrichment limit of the reactor core.
Specifically, we request to amend Technical Specification 1.3 to increase the maximum nominal fuel enrichment from 3.30 to 3.50 weight percent U-235.
The core design for Cycle 10, which uses 3.5 weight percent U-235, is a transition core to extend the operating cycle from 14 months to 18 months.
Cycle 10 is currently scheduled to begin in late May, 1987.
Eventually a fual enrichment of 3.7 weight percent U-235 will be necessary to attain an 18 month fuel cycle.
The change in fuel enrichment does not directly impact the results of the plant safety analysis. Many other factors relating to the actual core configuration have a greater influence on safety analysis results than the enrichment change proposed herein.
These factors include:
a.
The number and placement of fresh fuel assemblies, b.
the exposure distribution and placement of fuel assemblies remaining from previous cycles, c.
the number and placement of burnable poison rods, and i
d.
core operational strategy.
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MAINE YANKEE QTOMIC POWER COMPANY United States Nuclear Regulatory Commission Page Two Attention: Document Control Desk HN-86-147 l
These factors, among others, must be evaluated along with the specific fuel enrichment for each reload core design to demonstrate that the applicable acceptance criteria are met prior to core reloading.
This determination is made in accordance with 10 CFR 50.59 of the Commission's Rules and Regulations.
Thus, Technical Specification 1.3 simply places an upper limit on the maximum nominal fuel enrichment allowed in the reactor core with minimal impact on the plant safety analysis.
The operation of Maine Yankee with a maximum nominal fuel enrichment of 3.5 weight percent U-235 is being reviewed and evaluated for Cycle 10.
Each transient and accident considered in earlier safety analyses is being reviewed and reanalyzed where necessary.
Preliminary results indicate that the core design with 3.5 weight percent enriched fuel will meet the appropriate safety criteria. The storage of 3.5 weight percent enriched fuel in the spent fuel pool has been found to be acceptable and the evaluation has been approved in the NRC's Safety Evaluation, Reference (b). New fuel of 3.5 weight percent enrichment stored dry in the new fuel storage racks has been evaluated and found to be acceptable.
A description of the proposed change and a summary of Maine Yankee's significant hazards evaluation is presented in Attachment A.
As discussed in the attachment, this change does not involve a significant increase in the probability or consequences of an accident previously evaluated, the possibility of a new or different kind of accident from any accident previously evaluated, or a significant reduction in a margin of safety.
Therefore, this proposed change does not involve a significant hazards consideration as defined in 10 CFR 50.92.
A revised page 1.3-1 is included as Attachment B.
This proposed change has been reviewed by the Plant Operations Review Committee and the Nuclear Safety Audit and Review Committee. The Plant Operations Review Committee has concluded that this change does not constitute l
an unreviewed safety question.
A $150.00 application fee is enclosed pursuant to 10 CFR 170.12.
A state of Maine representative is being notified of this proposed change by copy of this letter.
l
MAINE YANKEE ATOMIC POWER COMPANY United States Nuclear Regulatory Commission Page Three Attention: Document Control Desk MN-86-147 Upon your review and approval of this amendment request, we request that the amendment be effective immediately.
Very truly yours, MAINE YANKEE ATOMIC POWER COMPANY John B. Randazza Executive Vice President JBR/bjp
Attachment:
(4 Pages) cc: Mr. Ashok C. Thadant Dr. Thomas E. Hurley Mr. Cornelius F. Holden Mr. Pat Sears Mr. Clough Toppan STATE OF MAINE Then perronally appeared before me, John B. Randazza, who being duly sworn did state that he is Executive Vice President of Maine Yankee Atomic Power Company, that he is duly authorized to execute and file the foregoing request in the name and on behalf of Maine Yankee Atomic Power Company, and that the statements ~therein are true to the best of his knowledge and belief.
f n f AM YMe%W Notary Public CERALDINE E. DOWNER NQ1ARY FtKEl' V<ft Di MAINE I
MY COi N.1
.0t4 Dw RES MAY 1, 1(JB8 8193L-SDE 1
M Al%E YANKEE ATOMIC POWER COMPANY ATTACHMENT A Descriotion of ProDosed Chance This proposal would change the maximum nominal enrichment of the fuel allowed to be used in the reactor core for operating Cycle 10 and beyond.
Maine Yankee is currently in Cycle 9 operation.
Maine Yankee proposes to change, in Technical Specification 1.3,
" Reactor", the fuel enrichment specification from a maximum nominal weight percent of 3.30 U-235 to 3.50 weight percent U-235. Changing the technical specification enrichment from 3.30 to 3.50 weight percent U-235 is acceptable since:
a) The adequacy of a given core design relative to the acceptance criteria must be demonstrated for each core prior to core reloading, and b) The facility's fuel handling equipment and storage areas have been analyzed and demonstrated to meet applicable acceptance criteria for an enrichment of 3.50 weight percent U-235.
Sionificant Hazards Evaluation Operation of the Maine Yankee plant in accordance with this change to its operating license has been evaluated using the standards in 10 CFR 50.92 regarding no significant hazards consideration. This proposed change does not involve a significant hazards consideration for the following reasons:
A.
This change will not involve a significant increase in the probability or consequences of an accident previously evaluated.
The propo wd increase in fuel enrichment does not affect the probability of the accidents previously evaluated.
The proposed change in enrichment does not increase the consequences of accidents previously analyzed. The adequacy of a given core design must be demonstrated for each core prior to core reloading.
The fuel enrichment is only one factor that must be considered in this determination. The fuel enrichment itself does not directly impact the results of the plant safety analysis.
Factors like the number and placement of fresh fuel assemblies, the exposure distribution and placement of the fuel assemblies remaining from previous cycles, the number and placement of burnable poison rods, and the core operational strategy have a more significant impact.
Preliminary results from an evaluation of the core loading planned for Cycle 10 (including a fresh fuel enrichment of 3.50 weight percent U-235) indicates that all applicable acceptance criteria will be met. Maine Yankee's determination for Cycle 10 will be documented in our Cycle 10 Core Performance Analysis Report which is under development and schedulec' l
for submittal in January, 1987.
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MAIPdE YANKEE ATOMIC POWER COMPANY 2-The facility's fuel and storage areas have been analyzed for enrichments of 3.5 weight percent U-235.
The results of these analyses indicate that handling and storage of 3.5 weight percent enriched fuel does not involve an unreviewed safety question.
The results of these analyses are within the acceptance criterion defined in Technical Specification 1.1, " Fuel Storage" of Keff less than or equal to 0.95.
Maine Yankee's application to increase the capacity of the spent fuel pool, which was approved in 1984 when the NRC issued Amendment 75 to Maine Yankee's Operating Licensing, assumed several conservative assumptions in the criticality calculations. This included:
Fresh fuel of 3.5 weight percent U-235.
No soluble boron in the pool water.
No axial or radial neutron leakage from the racks.
68'F water in the pool (the lowest anticipated temperature of the pool).
A value of boron loading in the BORAL plates such that there is a 957 probability that the boron concentration will, with 957.
confidence, be greater than that value.
Worst case values of mechanical parameters including center-to-center spacing, BORAL plate thickness, etc.
The effective multiplication factor (Keff) was less than 0.95 for the redesigned spent fuel storage racks when loaded with standard fuel assemblies iiaving a fuel enrichment of 3.5 weight percent.
The NRC's Safety Evaluation, Reference (b), found the results of the criticality calculation acceptable. The NRC also concluded, in Reference (b), that the effects of credible accidents on criticality had been considered and were shown to be bounded by the design calculations.
New fuel is stored dry in racks that have a center-to-center spacing of 20 inches (FSAR, Chapter 5).
This dimension provides a considerable margin of subcriticality even if the new fuel storage area were filled with demineralized water, Reference (c).
The new fuel storage area was analyzed for a fuel enrichment of 3.5 weight percent using NRC-approved methodology for the spent fuel pool. Conditions of varying moderator density, ranging from dry to flooded conditions, were considered.
The results of this analysis indicate that the acceptance criteria for Keff as identified in the Standard Review Plan (NUREG-0800, Section 9.1.1) are satisfied.
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M AINE YANKEE ATOMIC POWER COMPANY 3-An evaluation has also been performed to determine the effect of higher fuel enrichment on the fuel handling accident. The evaluation has resulted in the determination that an increase in fuel enrichment will not by itself affect the mixture of fission product nuclides.
Although a higher enrichment fuel cycle may result in fuel burnup consisting of a slightly different mixture of nuclides, the effect is insignificant because the isotopic mixture of an irradiated assembly is relatively insensitive to the fuel assembly's initial enrichment and the doses from postulated accidents are not significantly effected and continue to be acceptable.
B.
This change will not create the possibility of a new or different kind of accident from any accident previously evaluated.
Operation of Maine Yankee with 3.5 weight percent enriched fuel will not create any new or different kinds of accidents from those previously evaluated.
Fuel handling and storage of fuel with enrichment of 3.5 weight percent U-235 does not create the possibility of a new or different kind of accident from any accident previously evaluated.
C.
This change will not involve a significant reduction in a margin of safety.
The evaluation performed for each reload core assures that the core design meets appropriate safety limits, including a consideration of a significant reduction in the margin of safety. See response provided in Item A for information rertaining to the results cf preliminary evaluations performed for Cycle 10, the first reload core introducing 3.5 weight percent U-235 fuel.
The margin to criticality for fuel assemblies of 3.5 weight percent in the Maine Yankee fuel pool storage racks is not reduced and meets the NRC acceptance criterion of 0.95 for Keff, Reference (b), even with th9 many conservative assumptions used in the calculation of Keft astuming 3.5 weight percent fresh fuel. Similar conclusions have been rea:hed for the new fuel storage area.
Based on the above evaluation, this proposed change does not constitute a significant hazards consideration.
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MAINE YANKEE AYOMIC POWER COMPANY ATTACHMENT B j
1.3 REACTOR l
Acolicability Applies to the reactor vessel, vessel core and internals, as well as the Reactor Coolant System and components, including associated Emergency Core Cooling Systems.
Objectives To define those design criteria essential in providing for safe system operation which are not covered in Sections 2 and 3.
Specification A.
Reactor Core The reactor core shall contain 217 fuel assemblies with each assembly containing 176 rods.
Each fuel rod clad with Zircaloy-4 shall have a nominal active fuel length of 136.7 inches.
The fuel shall have a maximum nominal enrichment of 3.50 weight percent U-235.
]
The core excess reactivity shall be controlled by a combination of boric acid chemical shim, Control Element Assemblies (CEAs) and mechanically fixed non-fuel rods when required. The non-fuel rods may be fixed alumina-boron carbide, solid metal or open tubes.
There are a total of eighty-one (81) full-length, full-strength CEAs provided.
Forty (40) of these are paired to form twenty (20) dual CEAs.
Seventy-seven (77) CEAs, including all dual CEAs, are trippable.
Four (4) of the CEAs are nontrippable.
1.3-1 11/25/86 8193L-SOE
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