ML20033B259
| ML20033B259 | |
| Person / Time | |
|---|---|
| Site: | 07001100 |
| Issue date: | 11/09/1981 |
| From: | Ketzlach N NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| Shared Package | |
| ML20033B257 | List: |
| References | |
| NUDOCS 8112010125 | |
| Download: ML20033B259 (1) | |
Text
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Distribution:
Docket Eile 70-1100
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I NMSS rf FCUP rf NOV 9 1981 NKetzlach (2)
LTyson WTCrow JBlaylock RErickson DOCKET N0: 70-1100 JRobertson JRoth, R:I APPLICANT: Combustion Engineering, Inc.
GAJohnstone, CE FACILITY:
Windsor, Connecticut
SUBJECT:
REVIEW OF AMENDMENT APPLICATION DATED AUGUST 24, 1981 I.
Background
Combustion Engineering, Inc. (CE), by application dated August 24, 1981, requested authorization to decrease the center-to-center spacing between fuel assemblies within rows in their storage facility from 14 inches to 10 inches.
II. Discussion A.
Nuclear Criticality Safety 1.
Maximum Density From Sprinklers a.
CE Analysis 3
CE has estimated the maximum rist density to be 0.008 g/cm,
The following assumptions were made in their analysis:
(1) The pressure at the sprinkler head is 120 psi (no pressure drop in the lines).
(2) The time of travel of the water from the sprinkler head to the floor is 60 seconds.
(3) The shape of the discharge from a sprinkler is a parabolic solid having a radius of 12 feet at the floor (28 feet below the sprinkler head).
(4) The total flow from six overlaping sprinklers is six times that from a single sprinkler.
(5) The maximum thickness water film surrounding each fuel rod in an assembly is 0.055 cm.
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Staff Review of Assumptions The following are the staff cormnents on the assumptions made by CE:
(1) No pressure drop in the lines results in the maximum flow of water and is conservative for the nuclear criticality safety study.
(2) The time of discharge of the eater from the sprinkler head to the floor is difficult to estimate.
However, it should certainly be less than 60 seconds.
The time depends on droplet sizel which is a function of sprinkler head design and pressure at the sprinkler head.
Tnis assumption overestimates the mist density.
(3) A more conservative estimate by the staff of the spatial volume occupied by the sprinkler discharge indicates it to be 75 percent of that estimated by CE.
It was assumed the radius of discharge was 8 feet at a distance of 4 feet below the sprinkler heads and the discharge x
is cylindrical in shape in the retraining distance to the floor. Based on this model, the mist density is 33% greater than estimated by CE.
(4)
It is conservative to assume the total flow from six overlapping sprinklers i< ?ix times that from a single sprinkler at its maximum fgnw. The maximum flow density would be 0.011 g/cm compared to 0.08 estimated by CE. Greater mist densities are precluded by limiting fire fight)6g +.o the sprinkler system and to dry chemicals.
(5)
It has been determined by Dr. S. Fabic of the NRC Office of Nuclear Regulatory Research that the mist from sprinklers will form a water film approximately 0.013 cm thick on the surfaces of all rods in a PWR assembly. This film thickness was assumed by the staff in its nuclear criticality safety analysis.
i C. Yao and A. S. Kalelkar, "Effect of Drop Size on Sprinkler Performance,"
Meeting of National Fire Protection Association, May 21, 1970.
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NOV 91981 2.
Staff k,, Analysis The model used by the staff for the gU enriched CE assemblies nalysis was an infinite single plane array of 4.1 percent e3 containing a 16 x 16 array of fuel rods.
The center-to-center spacing between assemblies was 10 inches by 35 inches. Although the center-to-center distance between fuel assemblies inaadjacent double row racks is 37 inches, that between assemblies between rows within a double row rack is 35 inches. The method of analysis used the 123 neutron group GAM-THERMOS cross section set together with the KEN 0 Monte Carlo Computer program. The cross sections for the fuel rod lattices in the assemblief were resonance and Dancoff corrected using tne NITAM. Program 4 The method has been
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validated against experimental data for low enriched systems.
Calculations of k,, as a functiori of water mist density between units in the array were made.
Each rod in the fuel assembly was surrounded by a 0.013-cm-thick film of full density water. A 67-cm-thick water reflector was on top and bottom of the array.
Figure 1 is a plot of the k,, as a function of water mist density for the arrays in which the film thickness surrounding the fuel rods is.013 cm. Thg maximum k, is 1.115 and occurs at a mist densjtyof0.05g/cmJ.
The k,,is <l.0 at mis and <0.95 at mist densitf es <0.020 g/cmg densities <0.025 g/cm The CE Calculations were made for a finite array (19 x 34 assemblies) using fewer group ccess sections. The calculated maximum keff is 1.14 and occurs at a mist density of 0.06 g/cm3 It should be noted the keff on Page C-25 of the CE application is stated incorrectly.
That shown in their Figure D-1.11.1 (Page D-30 of the appliqation) is correct. The keff is <l.0 at mist densities <0.035 g/cm3 and
<0.95 at mist densities <0.03 g/cm. The differences in results of i
3 the calculations by CE and the staff are due to (1) the analysis of an array as a finite array and (2) the method used for the selection of cross sections. The staff method for the selection of cross sections is more exact. Based on the analyses made, it can be concluded that the CE storage array cannot be made critical under all credible degrees of water flooding.
2. M. Petrie, et al., "A Modular Code System for Generic Coupled Multigroup L
Neutron-Gama Libraries for ENDF/8," Section 7, ORNL/Tli-3706, March 1976.
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NOV 9 1981 It should be noted that measurements made during the Region.I~ (IE) inspection of the CE facility on August 25-28, 1981 (Report No.
70-1100/81-08) indicated the center-to-center spacing between assemblies within a row (in 6 cases of approximately 20 measurements nide) was as low as 131/2 inches when the minimum authorized spacing was 14 inches. Therefore, it is recomended a license condition be added authorizing the minimum center-to-center spacing between assemblies within a row to be 10.0 inches.
B.
Radiation Safety Since the licensee does not propose any changes in process operations, no significant effect on radiological safety should result.
C.
Environmental Effects Since the licensee does not propose any change in process operations, no significant change in environmental effect should result.
D.
General The amendment application was discussed with Mr. J. Roth, Region I (IE) inspector of the facility on October 27, 1981. He foresaw no safety or environmental related problem with authorization to decrease the spacing between fuel assemblies in the storage array.
III. Conclusion The controls associated with the storage of fuel assemblies at closer spacing are adequate for the protection of the health and safety of the operating personnel, the public and the en41ronment.
Issuance of the license amendment is recommended subject to the following condition:
Condition 31. The minimum center-to-center spacing between assemblies within a row in the fuel assembly storage room shall be 10.0 inches.
Original Signed by N. Ketzlach Norman Ketzlach Uranium Process Licensing Section Uranium Fuel Licensing Branch Division of Fuel Cycle and Y
original signed big Approved by:
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