ML20002C585
| ML20002C585 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 07/10/1974 |
| From: | Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8101100517 | |
| Download: ML20002C585 (3) | |
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\\q' l-F POWBr N_2:d C0mpBuy General offices: 212 West Michigan Avenue, Jackson, Michigan 49201. Area Code S17 788-0550 i
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z e: Docket 50-155 Mr. John F. O' Leary, Director License DPR-6 Directorate of Licensing US Atomic Energy Commission
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Big Rock Point i
Washington, DC 20545
Dear Mr. O' Leary:
Consumers Power Company made several commitments to be carried out during the refueling outage that was scheduled to commence in July 1974. Due to the short cycle that occurred between the start-up in early May of 197h and the shnidown in early June of 197h (a core average burnup of approximately h50 mwd /T), three of these commitments are being The commitments that are being deferred until the next refueling outage.
deferred involve the replacement of the initial type neutron sources (refer to our letter dated March 26,197h and Unusual Event Report 3-74 dated April 30,197h) and the gamma scanning of the cobalt corner rods (refer to Unusual Event Report 4-Th dated May 7,197h).
Consumers Power Company's letter of March 26, 1974 stated:
"It is planned to replace botn neutron sources and reinstall the activated antimony pins, from the original neutron sources.
The gamma source holddown device has been modified to provide a means of irradiating a new antimony pin while utilizing the new neutron sources.
(GE drawings 785-012 and 785-014). One of the original antimony pins will be removed from the reactor and a new antimony pin vill be inserted into the neutron source during the July-August 1974 refueling outage. The second antimony pin vill This co;rse be replaced during the succeeding refueling outage.
of action vill assure adequate neutron source strength throughout the changeover from the original neutron sources to the new neu-tron sources."
Because of the short length of the operating cycle, the antimony pin being activated in the modified gamma source holddown device did not receive sufficient radiation to obtain the minimum curie strength required Therefore, the to provide a sufficient number of ga=ma rays at start-up.
plans of antimony pin activation have been delayed until the next refueling The necessary neutron source strength might not be sufficient to outage.
allow start-up if the originally outlined plans were followed.
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Mr. John F. O' Leary Docket 50-155 License DPR-6 Big Rock Point July 10, 197h The original antimony pins were visually inspected during the last refueling outage (ending May 197h) and no indication of dimensional changes or metal attack were noted. Therefore, further irradiation of the original antimony pins is not expected to jeopardize the operation of the plant.
In Unusual Event Report 3-74, the failure of the original initial type neutron source beryllium-containing cylinders was attributed to an ex-cessive buildup of internal pressure. Under corrective action, Consumers Power Company committed to an inspection and measurement of the replacement source assemblies during each refueling outage. Due to the short length of the operating cycle, we have concluded that inspection and measurement of these source assemblies would serve no useful purpose and are, therefore, delaying the initial inspection until the next refueling outage.
Unusual Event Report 4-74 transmitted by letter dated May 7, 1974 stated as corrective action that gamma scanning of the cobalt. targets would be performed during the then planned July-August 1974 refueling outage to determine if further nonuniformities were forming. Since the operating cycle was shorter than planned (approximately 450 mwd /T), gamma scanning during the present refueling outage is not required. All of the high activity corner rods containing the suspect 11C5 capsules were removed during the last refueling outage. Therefore, significant gaps in the cobalt corner rods are not expected to exist at the present time and the gamma scanning has been rescheduled for the next refueling outage.
The unusual event report further stated that metallographic exami-nations vould be performed. These examinations have been initiated at Battelle Columbus Laboratories. Photographic records of the cobalt cap-sules have been taken and samples are being mounted per cobalt wire micro-structure examination. The work should be completed before it is necessary to manufacture the cobalt capsules for the next refueling outage. HovcVer, no conclusive information is available at the present time.
Yours very truly, RBS/ map Ralph B. Sewell Nuclear Licensing Administrator CC: JGKeppler, USAEC
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CONTROL NO: 6310 FILE: /heSO FROM:
DATE OF DOC DATE REC'D LTR TWX RPI CTHER Con;umers Power Company J:ckton, Mich 49201
-Mr. R.B. Sewell 7-10-74 7-12-74 X
TO; J.F. O' Leary 1 siRned CLASS UNCLASS PROP INFO INPUT NO CYS REC'D DOCKET NO:
XXX 40 50-155
" DESCRIPTION:
ENCLOSURES:
Ltr furn info concerning.....the replacement cf the Activated antimony pins in the neutron ACKNOWLEDGED ccurces.....
DO NOT REMOVE
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