ML19345A414
| ML19345A414 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 08/29/1969 |
| From: | Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| Shared Package | |
| ML19345A411 | List: |
| References | |
| NUDOCS 8011210337 | |
| Download: ML19345A414 (3) | |
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9 SA_FL"rY EVALUATION BY THE DIVISION _0LREACTOR_ LICENSING YANKEE ATOMIC ELECTRIC COM'ANY DOCKET No. 50-29 PROPOSED CHANGE NO. 88 INTP.0 DUCTION By letter dated August 26, 1969, Yankee Atomic Electric Company requested aut'aorization for transferring irradiated fuel inside a single assembly spent fuel cask from the vapor container through the equipment hatch to the spent fuel pit and vice versa Yankee has designated this request ai Proposed Change No. 88.
DISCUSSION The Ynnkee reactor was shut down on August 1,1969, for the scheduled loading of Core VIII.
During this refueling outage, irradiated fuel was transferred under water between the spent fuel storage pit and the reactor vessel utiliz-
.ing the fuel handling equipment described in the Final Hazards Summary Report in Section 218 which is incorporated by reference in the Technical Specifica-tions of License No. DPR-3.
Damage occurred to the fuel transfer carriage and has rendered the irradiated fuel transfer system inoperative thus prevent-in.', the completion of the refueling operation in the usual manner. Yankee now proposes to use a single assembly spent fuel cask for the remainder of this refueling outage for transferring four irradiated fuel assemblies from the shield tank cavity surrounding the reactor vessel opening to the spent fuel pit. and for returning two irradiated fuel assemblies from the spent fuel pit into the shield tank cavity. Each transfer wohldlinklude an approximate 90-foot vertical travel by use of the 150-ton polar crane inside the vapor i
l container for moving the suspended cask from the charging floor elevation I
through the open vapor container hatch onto a flat car at ground elevation below the hatch or vice versa.
EVALUATION The licensee proposes to use the single assembly spent fuel cask (BE Permit No. 1487) which has previously been approved by the AEC for handling and ship-ment of irradiated Yankee fuel assemblies. This cask has been designed for dissipation of fission product decay heat by external air convection cooling.
We have concluded that this 22-ton cask has acceptable structural, thermal and nuclear capabilities to be used for the proposed alternate method of irradiated fucI transfer.
Movements of the ISO-ton polar crane for transferring the cask from and to the shield tank cavlty will be accomplished without traversing the cask over the l
open reactor vessel, other vital equipment or piping. The cask would be 801121033 7
. tamporarily placed on the floor of the flooded shield tank cavity which has been designed to accommodate the larger reactor ve sel head and to sustain the greater floor loadings imposed by this 65-ton During this refuel-ing outage, the reactor vessel head will be temporarily stored in a lay-down area outside the vapor container.
The proposed alternate method for transfer of irradiated fuel will be performed only by trained Yankee operating personnel familiar with the single-assembly spent f2el cask. Detailed written procedures are being prepared and fuel trans fers will only be made in accordance with the approved procedures. In addition, thorough tests have been made prior to this refueling outage on the 150-ton polar crane system, including magnafluming of the crane hook, checking of the controls and testing of the brakes.
Comprehensive dynamic testing of this eraehasbeenperformedduringthisrefuelingoutagebysuccessfulcomplfflT)n of two transfer cycles with the 65-ton reactor vessel hesd along the ease paths of travel proposed for the cask. On the basis of the abova outlined steps being taken by Yankee, we conclude that accidental dropping of the cask is hip.ly unlikely.
l Although the probability of an accidental dropping of the cask containing a l
single irradiated fuel assembly is greatly diminished in view of the above outlined steps, the licensee has calculated the doses at the exclusion boundary, N
assuming that some"how the suspended cask were to drop from the highest eleva-tion just above thi charging floor inside the vapor container through the open I
equipment hatch onto the flat car at ground level outside the vapor container.
The licensee has further assumed that this drop would cause rupture of the cask and rupture of the cladding of all fuel rods of the contained assembly thus resulting in fission product release. On the basis of 30 days fission product decay since the beginning of this refueling outage, dif f asion parameters l
corresponding to PasquillType D and 2 meters per second wind speed, and release l
of 3% of the iodine inventory (the amount of iodine in the fuel assembly gap),
I the licensee calculat.; s negligible whr.,1e body dose (0.038 rea) and 13.2 ren dose to the thyroid.
Even for an assume release fraction of 50% rather than 31 of the iodine, the applicant's calcult.ted dose to the thyroid is 220 rens.
Our own calculations, based on our assred release fraction of 101 of all iodine, and using the licensee's meteo;ological parameters result in a dose to the thyroid of 60 reas. Our calculations also show a negligible whole body dose. The controlling thyroid dose reselting from the assemed dropping of the l
l cask is lower than the maximum accident dose (250 rem to the thyroid) at the excluslom boundary presented in the Final Hazards Summary Emport. Because the licensee can and will perform the remaining fuel assembly transfers under conditions as good cr better than Pasquill Type D and 2 meters per second wind speed, we conclude that the diffusion parameters used in the dose calculations are acceptable.
Further, the licansee has stated that he will install and have operable adequate instrumentation for determining the necessary minimum meteoro-logical conditions before proceeding with fuel transfers in the manner proposed.
b 3-In addition, the Ifeensee will include in the written procedures the methods to be used for -Jetermining the prevailing meteorological conditions and the requirement that fuel transfers shall not be carried out unless conditions are as good or battar than PasquillType D and 2 meters per secondsv/ bd specJ, CONCLUSIO;i On the basis of the foregoing considerations, we have concluded that fuel transfers by the alternate method proposed by the licensee do not present significant hazards considerations not described or implicit in the Final Hazards Summary Raport, and that there is reasonable assurance that the health and safety of the public will not be endangered by this operation in the man.ar propot,ed.
Therefore Yankee Atomic Electric Company is hereby authorized to cr>=plete transfer of irradiated fuel assemblies during the present refueling outage by the proposed alternate method.
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Donald J. Skovholt Assistant Director for Reactor Operations Division of Rasctor Licensing Date:
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