ML20030A524
| ML20030A524 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 02/02/1973 |
| From: | Lamley R, Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8101090895 | |
| Download: ML20030A524 (7) | |
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February 2, 1773 OA cn Mr. John F. O' Leary, Director Re: Docket No 50-155 Directorate of Licensing License No DPR-6 US Atomic Energy Commission Proposed Tech Washington, DC 20545 Spec Change No 36 Dear Mr. O'Ie Transmitted herewith are three (3) executed and thirty-seven (37) conformed copies of a request for change to the Technical Specifi-cations of License No DPR-6, Docket No 50-155, issued to Consumers Power Company on May 1,1964 for the Big Rock Point Plant.
This proposed change (No 36) will enable Consumers Power Company to replace the original auxiliary neutron sources that were repaired in 1972 after failure of the secondary encapsulations (reference information letter dated April 19,1972). The original auxiliary neutron sources will be removed after the new auxiliary neutron sources have been in the core for one operating cycle.
In addition, these new auxiliary neutron sources are of a design compatible with our future 11 x 11 array fuel bundles.
To prevent secondary encapsulation failure of these new auxiliary neutron sources, additional precautionary measures have been implemented to prevent internal contamination of the neutron source assemblies.
It is our intention to insert these new auxiliary neutron sources into the Big Rock Point reactor during the March 1973 refueling outage. We would, there1 ore, appreciate an expeditious handling of this request for a Technical Specifications Change so that we might receive approval before March 1, 1973 Yours very truly, Aw& A7 WGF/ map Ralph B. Sewell Nuclear Licensing Administrator CC: BHGrier, USAEC 915 '
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- 1. -
l CONSUMERS POWER COMPANY Docket No 50-155 Request for Change to the Technical Specifications Change No 36 License No DPR-6 For the reasons hereinafter set forth, the following changes to the Technical Specifications of License DPR-6 issued to Consumers Power Company on May 1, 1964, for the Big Rock Point Plant are requested:
I.
Section 5 A.
Change Section 5 1.6 to read as follows:
" Type Antimony Beryllium Quantity Two Initial Sources Up to Four Auxiliary Sources
- Location The initial neutron sources shall be placed in core positions 02-59 and 09-52 as shown in Figure 5 1.
Two auxiliary neutron sources may each be contained in a re-1 movable red in a fuel bundle located one fuel bundle position frce the outside of the core, symmetrically near the east-west line through the center of the reactor core. Two additional auxiliary sources may each be contained in a removable rod in a fuel bundle located in an opposite quadrant from the first two auxiliary sources (ie, the two additional auxiliary neutron sources will not be located in the easternmost 12 fuel bundle 4
quadrant defined by Row 57 and Column 07 or the westernmost 12 fuel bundle quadrant defined by Row 54 and Colu::= 04).
The initial neutron sources shall consist of a steel-jacketed
^
antimony pin,1 inch diameter by 12 inches long, centrally located on the vertical axis of a steel-jacketed (Type 304 SS)
- With in-vessel low-level neutron detectors in service, one operating source may be temporarily relocated as the operator deems, appropriate.
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" beryllium cylinder 5-1/2 OD by 16 inches long. The entire assembly, including support structure, is a cylinder 79-7/16 inches long by 6 inches diameter which rests on a special ori-fice in a standard support-tube-and-channel assembly. A lifting bail shall be provided for handling purposes. The assembly de-sign shall allow adequate cooling along the surface of the source pin and the cuter surface of the assembly.
The auxilian neutron sources shall each consist of a homogeneous 50-50 mixture of antimony-beryllium first encapsulated in a steel tube (Type 304L SS), then secondarily encapsulated in a zirconium alloy tube. Each doubly encapsulated source will be equipped with a spring-loaded, bayonet-latch locking device to permit it to be locked into a corner fuel rod position in a fuel bundle."
II. Discussion - Additional Auxiliary Neutron Sources A.
Reason for Additione.1 Auxiliary Neutron Sources Failure of secondary encapsulation welds on the existing auxiliary neutron sources (as reported in our April 19, 1972 letter to Dr. P. A. Morris) dictated that they be replaced. It is necessary to insert the replacement (n:w additional auxiliary) sources into the reactor for one cycle to acti-t l
vnte them prior to their use as replacement for the existing auxiliary sources.
In order to improve emergency core cooling system performance and in anticipation of better fuel performance, we intend to replace during the next four-year period the existing 9 x 9 fuel bundle design with an 11 x 11 fuel bundle design. The new sources, therefore, have a smaller diameter to fit in the new fuel bundle design. Since there will be a very limited number of 11 x 11 fuel bundles available for the next cycle, it is necessary to insert into the reactor the new auxiliary sources in the two Xenon Nuclear Reload "G" Lead Bundles (described in our June 16,1CJ72 sub-
- mittal for Change No 31 to the Technical Specifications). We are asking for some latitude in placement of the new auxiliary sources so that the intent of the lead fuel bundle program will not have to be unduly compro-mised in the final fuel loading scheme for the next cycle.
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3 B.
Description of Additional Two Auxiliary Neutron Sources The neutron source material is a homogeneous mixture of 50-50, by volume, antimony-beryllium compacted to a minimum packing fraction of 80%.
The source material is first encapsulated in a 0 374 inch OD steel tube (Type 304L SS) with a 0.028 inch wall thickness. The overall length of the source tube is 70.110 inches with the source material located in the middle 44.26 inches, held there by a hollow, steel tube spacer at each end.
The remaining space in the source tube is void volume. The source tube is encapsulated in a zirconium alloy fuel tube of exactly the same quality and dimensions as tubing used for fuel rods and cobalt targets. The locking mechanism and rod configuration are exactly the same as the renovable cobalt rods and removable fuel rods. To distinguish the auxiliary neutron source from cobalt targets, the nut on the bayonet-latch type locking mechanism is square rather than hexagonal. It is large enough to be visible through both the reactor and fuel pool water. The square nut is also large enough so that the hexagonal rod removal tooj will not fit it.
C.
Auxiliary Neutron Source Design The in-reactor design life of the auxiliary neutron sources is 15 years. Sufficient void volume has been incorporated into the design to attain this objective. Based on an assumption of 1.5 x 10 n/cm-s for the flux of neutrons with energies greater than the 2.7 MeV threshold for the (n, 2n) and (n, alpha) reactions in beryllium, approximately 2 5 x 10 He atoms would be generated in 15 yeare. m ing 799 5 F as the tem-perature of the outer surface of the stainless steel capsule and assuming conservative conductivity values, the peak temperature in the source ma-terial would be 870 F.
The internal capsule pressure developed, after 15 years of irradiation, would be 1127 psia. The minimum wall thickness of 0.027 inch exceeds the minimum thickness specified by the ASME Pressure Vessel Code for 304L SS stressed under the above conditions of pressure and temperature.
(Rules of Construction of Pressure Vessels, Division 1, 1971 Edition, ASME Boiler and Pressure Vessel Code Section VIII and sup-plements through summer 1972.)
4 D.
Quality Assurance Program Improvements to the Product Specification's Materi'al and Quality Assurance Requirements provide additional assurance that the mechanical
(
h integrity of the new neutron sources will be maintained. Quality Assur-ance requirements were specified in the original bid specifications and were adhered to throughout manufacture. Detailed weld and manufacturing procedures were developed, reviewed and approved. Detailed leak-test procedures were also reviewed and approved. Material certifications of the physical and chemical composition of all the source components were reviewed and approved. In most instances, copics of these certifications were sent directly to Consumers Power Company. Design calculations were also reviewed and approved. In general, the Quality Assurance program applied to the design, procurement and manufacture of the sources was con-sistent with the program applied to nuclear fuel.
E.
Nuclear Characteristics The replacement of a 35 g/ft cobalt target with one of the pro-posed auxilicry neutron sources would have a minor effect on the nuclear characteristics of the fuel bundle. The following changes would occur in a typical, fresh Reload "G" fuel bundle:
1.
The two outside fuel rods adjacent to the neutron source have approximately a 6% increase in the local (rod-to-rod) peaking factor. The overall fuel bundle maximum local peaking factor is increased by approxi-mately2-1/2%.
2.
The fuel bundle reactivity is increased by approximately 0.6%.
Both of the above changes are caused by the lower absorption rate associated with the neutron sources. Neither change he.s a significant effect on the operating limits for the fuel bundle. As designed, each 8
auxiliary source is capable of yielding 1.5 x 10 n/s following irradia-13 2
tion fer six months at a reactor thermal flux of 10 n/cm
,3, F.
Planned Operating Procedures Current plans call for the additional two auxiliary neutron sources to be inserted into the core during the March 1973 refueling outage. The neutron source activity will build up to a useful level by the end of the next operating cycle.
During the 1974 refueling cutage, the original auxiliary neutron sources will be removed from th'e reactor core, and the new auxiliary neu-tron sources will be placed in the core locations previousb occupied by the old auxiliary neutron sources.
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5 G.
Hazards Considerations The main hazards considerations relate chiefly to the effect that the additional auxiliary neutron sources will have on start-up count rates.
Since the second pair of auxiliary neutron sources will be located farther away from the start-up detectors than the original auxiliary neutron sources, any increase in start-up count rate will be due to fission neutrons.
Other hazards considerations relate to the dose rates at the fuel transfer cask surface. Calculations at the fuel transfer cask surface, assuming no shielding effect of the cask material, show a dose rate of 180 mrem / hand,atthreefee'tfromthecasksurface,showadoserateof 20 mrem /h. This is well within normal dose rates occurring during nomal fuel handling operations.
The possibility of inadvertently inserting a fuel bundle containing a neutron source into the center of the core has also been considered.
Peaking factors for the fuel bundle are not sufficiently different to have a substantial effect on the operating limits. Additionally, because of the conservative mechanical design, there would be no adverse effects on the integrity of the source.
III. Conclusions Considering the analyses presented herein, we have concluded:
1.
The mechanical and physics design of the auxiliary neutron cources are conservative and compatible with other core components.
2.
The addition of two new auxiliary neutron sources will not adversely affect existing source-to-detector geometry or degrade the start-up count rate. When sufficiently irradiated, they will replace the present auxiliary sources.
Based upon this, we have concluded that the use of two additional
" Auxiliary Neutron Sources" in the Big Rock Pcint Plant does not present a change in the hazards considerations described or implicit in the Final Hazards Summary Report.
CONSUMERS POWER COMPANY.
By:
- f I
R. A. Lamley, Vice President Date: February 2, 1973 Sworn and subscribed to before me this 2nd day of February 1973 YMb { f ad Notar r Public, Jackson County, Michigan My commission expires June _20,1976
AEC DI." UBUTION FOR PART 50 DOCT MAPIAL (TEMPORARYJORM)
CONTROL NO:
915-
't n2 FROM:
DATE OF DOC:
. Conskmers Power Coqiany Jackson, Michigan 49201 Palph B. Seve11 2-2-73 2-6-73 X
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Mr. O'Icary 3 signed CIASS:, p0F IiiF0 INPUT lio CYS REC'D
, DOC.E.7 4i0:
X 40 50-155 DESCRIPTION:
ENCLOSURES:
Ltr trans the following:
Request for Change to Tech Specs (No. 36),-
notarized 2-2-73, for the Big Rock Point Plant.
( 40 cys rec'd) DO Not R9mbie PLAhT KAMES: Big Rock
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