ML20205L236
| ML20205L236 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 10/25/1988 |
| From: | Lippold W BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20205L237 | List: |
| References | |
| NUDOCS 8811010534 | |
| Download: ML20205L236 (4) | |
Text
.
o O
BALTIMORE GAS AND i
ELECTRIC i
CHARLES CENTER e P.O. BOX 1475 BALTIMORE. MARYLAND 21203 NUCLEAR ENGINEERING SERVICES DEPARTMENT cAtytet curra NUCLEAR PoWrtR PLANT LUSOY. MARYLAND 206S7 October 25, 1988 v
U. S. Nuclear Regulatory Cocunission
-l 1 White Flint North 11555 Rockville Pike
'Rockville, MD 20850 ATTENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos. 1 & 2; Docket Nos. 50 317 & 50 318 Increase to Enrichment Limits
REFERENCES:
(a)
Letter, J. A. Tiernan (BG6E) to Document Control Desk j
?
(NRC), dated June 9,1988, Request for Amendaent (b)
Letter, S. A.
McNeil (NRC),
to J.
A. Tiernan (BG6E),
[
dated September 30, 1988, Request for Amendment t
4 Centlemen:
This letter is in response to Retirence (b). We believe that this addresses all questions and concerns regarding R3ference (a),
j T
Reference (a) proposed changes to the Technical Specifications related to the enrichment limits for storage in the, new and spent fuel storage racko.
3 1 provides the additional infot.ation requested. This information l
m l
l does not affect the Determination of Significant Hazards Considerations as l
provided in Reference (a).
[
I Should you have further questions regarding this matter, we will be pleased to j
L discuss them with you.
l!
Very truly yours, j
s M
l
.J.L pold j
General Supervisor -
Technical Services Engineering 3
VJ L/RilB/Imt r
.b 0
Attachment gg 8911010534 se1025 g
}
ADOCK0500g7 i
PDR P
on, 4
t' 1
1 E
o s
i
- hi.
e n' ' ~
.Docus et Control D;ak
~
0ctobir*24, 1988 JJ Pagei2
. t:
..f 5.
cet
.D. A. Brune, Esquire s
J.'E, Silberg, Esquire R. A.,Capra, NRC
(,
't :
S A, McNeil, NRC
,W T. Russell, NRC D, C. Trimble/V. L. Pritchett, NRC T. Magette, DNR l
l
o ATTACHMENT 1 Item i NRC Request The staff's position on the criticality of unirradiated fuel sto*.ed in the new fuel storage racks is that keff will not exceed 0.98 if accidentally moderated by the extreme low density water or other hydro;enous material such as may occur for fog, mist, and firefighting foat.
The new fuel storage facility must also be designed so that keff wil) not exceed 0.95 if accidentally fully flooded with pure water.
Both of t'.iese conditions have been analyzed and stated to have been met.
- However, Technical Specification (TS),
Criticality-New Fuel",
on'.y refers to the 0.98 criterion.
Since this TS is being modified to increase the enrichment limit, we recommend that it also be modified to include the 0.95 criterion as well.
BC&E Responso Proposed Technical Specification "Criticality New Fuel" has been modified as recommended to read "...
keff will not exceed 0.95 when fuel having a maximum enrichment of 5.0 weight percent U-235 is in place and various densities of unborated water are assumed including aqueous foam moderation and full flood conditions.
The keff of 0.95 includes the conservative Item 2 NRC Request The reactivity effect of a possible 4-inch gap et the centerline of every Boraflex sheet was analyzed and found to neet the staff's limiting criterion. Justify that gap formation larger than this, in size and extent, would not occur and describe any monitoring program at Calvert Cliffs which would detect degraded Boraflex sheets including possible gap formation.
BC&E Responso The 4.0 inch gap was considered a worst case analysis.
The 4.0 inch gaps were placed on the centerline of the stored fuel and assumed to be uniform in an infinite array of storage cells.
Further review of Bisco's irradiation of Boraficx indicates that the maximum reduction in length would be about 3.5 inches.
The probability that this reduction would result in gapping on the same plane in the racks would be very low.
Even with the gap of 4.0 inches on the same plane, the above analysis increased the koff by only 0.00436 over the no gap case.
Since the Boraflex sheets were not adhesively constrained during installation, the likelihood of gap formation at the centerline is minimized.
1
A poison coupon monitoring program is carried out to determine the extent, if any, of weight loss, reduction in size, or degradation in appearance of poison material. To date, no notable degradation has been observed.
Item 3 NRC Request flow were the uncertainties in the manufacturing tolerances of U 235 enrichment and fuel pellet density considered in the determination of the 95/95 confidence level uncertainty?
BC6E Response The enrichment limit is based on the maximum enrichment including the uncertainty.
The fuel pellet density did not include the density variation in the specification.
The specification for pellet density is 93.5% to 96.0% of theoretical density of UO2. The density used in the analysis was 10.35 gm/cm3 or 94.5% of theoretical density of Uo2. The keff was analyzed for fuel pellets at 96.0% of theoretical density of UO2, which resulted in an increase in the keff above the nominal case by 0.001193.
This was included in the uncertainty calculation using the square root of the sum of the squares of the other uncertainties which was added to the nominal koff resulting in a maximum keff - 0.945.
This is the same keff without the pellet density uncertainty with both results rounded up to the highest thousandth.
Item 4 NRC Request TS 5.3.1, "Reactor Core-Fuel Assemblies," places a maximum enrichment limit of 4.1 weight percent U-235 on reload fuel located in the reactor core.
When do you intend to request that this limit be raised? To what value will you propose to raise it? What accident analyses do you intend to perform to justify an increase in this limit?
BC6E Response The reload submittal for Unit 2 Cycle 9 will be submitted on or before February 10, 1989.
The reload enrichment will be 4.3 percent U 235 All transient analyses under Chapter 14 will be evaluated to support the reload.
2