ML19207B254
| ML19207B254 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 08/01/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19207B250 | List: |
| References | |
| NUDOCS 7908230680 | |
| Download: ML19207B254 (3) | |
Text
a"'ag UNITED STATES
'g'g
+
NUCLEAR REGULATORY COMMISSION
!j
~(
WASHINGTON. D. C. 20555 E
- e..
E
%,...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING THE FUEL HANDLING ACCIDENT INSIDE CONTAINMENT DRESDEN NUCLEAR POWER STATION' UNIT 1 COMMONWEALTH EDISON COMPANY DOCKET NO. 50-10 INTRODUCTION By letter dated January 17, 1977, the staff requested the Commonwealth Edison Company (the licensee) to evaluate the previously unevaluated potential conse-quences of a postulated Fuel Handling Accident Inside Containment (FHAIC) at Dresden Unit 1.
The licensee submitted, in a letter dated March 18,1977, an evaluation of the FHAIC.
In the licensee's evaluation, he assumed that all the fuel pins in the equivalent of a single fuel assembly failed following the dropping of a fuel assembly onto the top of the core.
The licensee stated that the potential consequences of this postulated accident are 11 Rem thyroid and 0.05 Rem whole body at the Exclusion Area Boundary (EAB).
The licensee con-cluded that these doses are well belcw the guidelines of 10 CFR Part 100.
EVALUATION Ue have completed our review of the licensee's March 18, 1977 submittal and concluded that the consequences of the accident postulated by the licensee are within the guidelines of 10 CFR Port 100 and therefore are acceptable.
During the refueling operations a fuel transfer basket is loaded with 16 spent fuel assemblies and is then transported from the north sump, to the fuel transfer tube and down the fuel transfer tube using an overhead crane.
Failure of the overhead crane during this operation could be a more severe accident than that dssumed by the licensee.
Therefore, we analyzed the consequences of this accident assuming that all the pins in 16 fuel assemblies failed.
The assumptions and results of our analysis are given in Table 1.
The calculated potential doses at the EAB from this accident are 56 Rem thyroid and 0.4 Rem whole body dose.
The limiting dose of 56 Rems is within the guidelines of the 10 CFR Part 100 value of 100 Rem.
The whole body doses are not controlling due to the decay of the short-lived radioisotopes prior to fuel handling.
Since the refueling crane is positioned above the core or between the core and the fuel transfer basket during fuel handling, the fuel transfer basket itself cannot be dropped onto the core and therefore this accident was not considered credible.
Analysis of dropping a spent fuel assembly during maneuvers in the spent fuel pool resulted in no calculated fuel pin damage to the dropped or target fuel assemblies.
' 0 F, j [t,
280 hf)
_2_
Our conclusions are that:
(1) the limiting accident is the drop of the fully loaded transfer basket down the fuel transfer tube and (2) the postulated con-sequences of the limiting accident are within the guidelines of 10 CFR Part 100 and are, therefore, acceptable.
ENVIRONMENTAL CONSIDERATIONS The environmental impacts of an accident involving the handling of spent fuel inside containment have been addressed in Section 7.1 of the Final Environmental Statement (FES) dated November 1973, for the operation of Dresden Nuclear Power Station Unit 1.
Date:
August 1, 1979
'\\ b >
..c
Table 1 ASSUMPTIONS FOR AND POTENTIAL CONSEQUENCES OF THE POSTULATED FUEL HANDLING ACCIDENTS AT THE EXCLUSION AREA B0UNDARY FOR DRESDEN STATION UNIT 1 Assumptions:-
Guidance in Regulatory Guide 1.25 Power Level 700 Mwt Fuel Exposura Time 3 years Power Peaking Factor 1.5 Equivalent Number of Assem-blies damaged 16 Number of Assemblics in core 464 Charcoal Filters available None Decay time before moving fuel 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 0-2 hours X/Q Value, Ex-clusion Area Boundary
-4 3
(ground level release) 1.0 x 10 sec/m Doses, Rem Thyroid Whole Body Exclusion Area Boundary (EAB)
Consequences from Accidents Inside Containment 56 04
'l b.,
3