ML20236C272
| ML20236C272 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 03/15/1989 |
| From: | Creel G BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-PT21-89, REF-PT21-89-027-000 PT21-89-027-000, PT21-89-27, NUDOCS 8903220051 | |
| Download: ML20236C272 (3) | |
Text
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BALTIMORE OAS AND ELECTRIC CHARLES CENTER. P.O. BOX 1475 BALTIMORE, MARYLAND 21203 March 15,1989 s
U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 10 CFR Part 21 Written Report: Nuclear Fuel-Potential Loss of Shutdown Marnin Gentlemen:
Baltimore Gas and Electric has discovered a condition that we believe meets the criteria of a defect in a basic component as defined in 10 CFR 21. ' This letter provides the information required to be reported to the NRC pursuant to 10 CFR 21. A verbal notification was made to your Mr. David Limroth of the Region I headquarters on March 10,1989.
Facility:
Calvert Cliffs Units I and 2 Component:
Nuclear Fuel Design Consulting Services Firm:
Combustion Engineering (CE)
Nature of Defect:
Over the course of the last several fuel cycles, we have increased the enrichment of our fuel. In the current cycle, we are loading 4.3 */o fuel in the core. Some of the fresh fuel assemblies are highly reactive (k
1.0) under refueling conditions. Is part of the core design consulting services, CE provided confirma-tion that the refueling boron concentration is sufficient to maintain k
< 0.95 for configuration.pp e
the final core However, our refueling procedures, which are
'l consistent with Regulatory Guides, allowed placement of fuel assemblies in intermediate positions during core alternations.
A significant amount of reactivity could be l
ff!){hkl
y Document Control Desk March 15,1989 Pa8e 2 added to a subcritical geometry by placing a highly - reactive. fuel assembly in certain intermediate positions.
In.the
- past, we have relied _ on suberitical multiplication to detect. 'an impending criticality-during refueling. With the - highly. reactive fuel, suberitical multiplication may no longer provide adequate warning of 'an approach to criticality.
Safety Hazard:
During refueling the : potential. has existed
.for placing several new fuel assemblies together and. lor,ing some of the required 5%'
shutdown margin, or in the extreme, having_
an inadvertent
' criticality.
CE, as fuel
- designer, had
- access to information JI concerning - the ~ reactivity of individual, fuel j
. assemb1hs that could have alerted them to this potential. However, we did not. ask
- for, nor did
_they. provide, information concerning the potential of the fuel to form critical systems.
No information was provided concerning the assumptions implicit in their analysis.
We independently discovered this potential condition. during a review of Information Notice 88-21.
Date Information Verified:
March 10,1989 Number of Components:
This condition affects between 10 and 20% of the fuel assemblies in the core.
Corrective Actions:
(1) We have requested a k, listing from CE which will indicate the reactivity of each fuel assembly, and: (2) We will revise our refueling procedure prior to the next use to ensure that a fuel bundle.will not be placed.
in an intermediate ' position. during core alternations without '
first_
verifying
_its potential -
reactivity.
When _
these
'two actions are ' completed, fuel will only be positioned in intermediate. core. locations which will contain fuel of equal or _ greater reactivity in the final core configuration.
Manufacturer's Advice:
CE is issuing an information bulletin concerning shutdown margin during refuelin3 4
C____________
s:
' Document Control Desk March 15,1989 Page 3 Should you have,any further questions regarding this matter, we will be pleased to discuss,them with you.
Very truly yours, 1
l George C. Creel Vice President - Nuclear Energy GCC/ PSF /dtm I
cc:
D. A. Brune, Esquire f
J. E.
Silberg, Esquire f
R. A.Capra, NRC S. A.McNeil, NRC W. T. Russell, NRC j
V. L. Pritchett, NRC i
1
.