ML20002A395
| ML20002A395 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 07/30/1964 |
| From: | Boyd R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| References | |
| NUDOCS 8011170059 | |
| Download: ML20002A395 (2) | |
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UNITED STATES ATOMIC ENERGY C 004ISSION HAZARDS ANALYSIS BY THE RESEARCH AND POWER REACTOR SAFETY BRANCH
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DIVISION OF REACTOR LICENSIraG IN THE MATTER OF
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YANKEE ATOMIC ELECTRIC COMPANY w.
PROPOSED CHANGE NO. 57 l
DOCKET No. 50-29 1
i Introduction-Pursuant to the provisions of Section 50.59 of the Commission's regulaticas, 1
i Yankee Atcmic Electric Company in Proposed Change No. 57, dated July 3, R
1964, requested authorization of a change in the Technical Specifications attached as Appendix A to License No. DPR-3.
This Proposed Change would authorize the proposed loading configuration of Core IV, use of soluble boron in the primary coolant system in concentrations up to 1300 ppm, and irradiation of a test fuel assembly to an exposure of 30,000 MWD /T.
Discussion Cere IV is an extension of the cultiregion loading pattern initiated with
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Ccre III. Thirty-six new 4.1% enriched fuel elements will be installed in the peripherel region (Region C), and the 4.1% elements irradiated in this region in Core III vill be moved toward the center (Region B). The central four elements (Region A'j in the reactor will consist of three 3 4%
elements irradiated at this location during Cora III and one test assembly
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that accumulated a total exposure of 22,000 MWD /T during operation of Core I and Core II.
The excess reactivity of Core.IV will be higher than that of Core III since nearly all of the fuel elements are either. new 4.1% enriched or 4.1%
enriched elements which have been irradiated for one core cycle. The ccre loading pattern will provide a flatter radial flux distribution which U
will lower the maximum exit temperature from 611 F to 607 F.
The rod pregramming for Core IV hes been. modified to control the reactor using the central.12 centrcl rods (rod groups 1-4). The applicant has analyzed i '
the hot channel facters under this mode of operEfon and' reports that the i
minicum DNB ratio for_ core _IV._will.be_2.75.
The authorized minicum DNB The increase
\\'\\ratiosforCoresIIandIIIwere2.20and2.35,respectively.
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in.,the calculated DNB ratio should result in a more conservative method of
} operation than that analyzed in conjunction with the proposed operation of j Cores II and III.
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7 i The reactor will be contro11'd at power by moving control rod groups 3 e
and 4 together and groups 1 and 2 together. The hot channel facters during
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centrol with groups 3 and 4 are higher than with groups 1 and 2 and could result'in a significant decrease in the DNB ratio. To maintain the' minimum DN3 ratio of 2.75 during the time that groups 3 and 4 are controlling, the
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reactor power will be limited to 540 MWt.
This initial period of operation is expected to last about one week.
The increased core reactivity and modified control rod progra= ming will require boron concentration in the moderator for a short period of ' operation with Core IV.
Yankee plans to determine the boron equivalent of equilibrium xenon and proposes to operate with the boron concentration up to 1300 ppm during the test period. We do not believe that operation with increased a
boron concentrations in the moderator will present any significant eafety problems.
No difficulties were experienced at Yankee during the previously
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authorized use of soluble boron, and the Saxton reactor has operated satis-factorily with boron concentrations up to 1200 ppm for nine months.
The irradiation'of a fuel element in Region A to a total exposure of 30,000 MWD /T is under a test program sponsored by the New York Operations Office of the Atomic Energy Commission. This element will contain a greater fission product inventory than the elements normally irradiated in the reactor.
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However, since this element represents less than 2% of the total core volume, its use does not present a significant change in the accidents previously
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Cenclusion We hsve cencluded that the Proposed change does not present significant hazards considerations not described or implicit in the hazards su=zary report, and that there is reasonable assurance that the health and safety cf the public will not be endangered.
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opginal signed tr.
pgu S. byd Roger S. Boyd, Chief Research & Power Reactor Safety Branch Division of Reactor Licensing I
Date:
JUL 3 0 ES4 l