ML20138B139
| ML20138B139 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 10/09/1985 |
| From: | Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19273A636 | List: |
| References | |
| NUDOCS 8510150110 | |
| Download: ML20138B139 (15) | |
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PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET P.O. BOX 8699 PHILADELPHIA. PA.19101 (zts) sat sozo M. J. COON EY l
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October 9, 1985 l
I Docket Nos. 50-277 50-278 Mr. John F.
Stolz, Chief Operating Reactors Branch #4 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C.
20555
SUBJECT:
Peach Bottom Atomic Power Station, Units 2 and 3 Installation of New Spent Fuel Storage Racks
REFERENCE:
Letter, John F.
Stolz to E.
G.
Bauer, Jr.
September 5, 1985 - Request for Additional Information
Dear Mr. Stolz:
On June 13, 1985, Philadelphia Electric Company submitted a request for approval of new spent fuel storage racks for Peach Bottom Atomic Power Station.
By letter dated August 1, 1985, Philadelphia Electric Company provided the Nuclear Regulatory Commission with a revised submittal which contained the complete analyses and Safety Evaluation in support of the earlier request.
During review of the submittal, the Commission staff found areas requiring further clarification and on September 5, 1985 requested additional information.
The response to the request for additional information is provided in three separate attachments:
e Attachment A - Response to Questions 231.2, 450.1, 450.2, 450.3, 450.4, 450.5 and 450.6.
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Mr. John F. Ctolz October 9, 1985 Page 2 e
Attachment B - Response to Question 231.1 and Affidavit by W.
H. Griffith, General Manager, Nuclear Components
-Division, Westinghouse Electric Corporation.
For the reasons stated in the Affidavit, it is hereby requested that the response to Question 231.1 in Attachment B be withheld from public disclosure in accordance with
'Section 2.790(a)(4) of the Commission's Regulations.
e Attachment C - Response to Questions 1 through 8, which were quest' ions asked by the Franklin Institute in its review of the submittal.
Should you have any questions or need additional information, please do not hesitate to contact us.
V ry truly yours, f
j k/4LC i
Attachments j
cc Dr. T. E. Murley, Administrator, Region I, USNRC 1
T.
P. Johnson, Resident Site Inspector i
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' October, 1985 Dockst No2. 50-277
.50-278 RESPONSES 'IO LETTER, J.
F. STOLZ TO E. G. BAUER, JR.
SEPTEMBER 5, 1985 - REQUEST FOR ADDITIONAL INFORMATION PEACH BOTTOM A'IOMIC POWER STATION UNITS 2 AND 3-INSTALLATION OF NEW SPENT WEL RACKS ATTACHMENT A e
Page 1 of 7, Answer to Question 231.2 e
Page 2 of 7, Answer to Quest.,on 450.1 e
o Page 3 of 7, Answer to Question 450.2 e
Page 4 of 7, Answer to Question 450.3 e
Page S of 7, Answer to Question 450.4 e
Page 6 of 7, Answer to Question 450.5 e
Page 7 of 7, Answer to Question 450.6 a
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. Attechnent A Pegi l of 7
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231.2 QUESTION:
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.The present Peach Bottom Technical Specifications limit storage in the spent' fuel racks to assemblies having less than 17.3 grams /cm of U-235 in their dominant (most reactive) portions. 'Please confirm that this
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value is consistent with 3.5 percent enrichment or alter the Specification to conform to the correct value.
f RESPONSE:-
J.
17.3' grams /ca of U-235 in the dominant (most reactive) portions of spent fuel assemblies is a value calculated by the NRC in the generation of the current Technical Specifications. The Licensing Submittal Design Report for High Density Spent Fuel Racks dated 1/78, Section 4.2, Analysis Basis, I-
-states the design criteria used in the existing rack criticality analysis i -
-was 3.5 w/o U-235. Using the fuel assembly parameters in the 1/78 Des'ign Report, we have confirmed that the 17.3 grams /cm value used by the NRC is j
consistent with-3.5 percent U-235 enrichment, i
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Attcchm:nt A Pcga 2 of 7 7
450.1 QUESTION:
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Discuss the anticipated burn-up of the highest burn-up assenbly to be stored in the new high-density spent fuel storage racks.
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RESPONSE
j The design limit discharge burn-up for the current 8x8 j
reload fuel being used at Peach Bottom is 38,500 MWD /MTU, j
with the exception of seven lead test assenbiles which are
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expected to be discharged with burn-ups on the order of i
44,000 MWD /MTU.
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The thermal hydraulle analyses performed for the new spent i
fuel racks assuned a current discharge average burn-up limit of 40,000 MWD /MTU, and added conservatism in orded to account for higher burn-up fuel which is anticipated for future storage in the racks. The conservatism resulted in a
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maximun fuel assenbly decay heat generation rate of 11.39 BTU /SEC. The decay heat curve given in NRC Branch Technical l
ll Position APCSB 9-2, " Residual Decay Energy for Light Water h
Reactors for Long Tenn Cooling", would predict a decay heat i
rate of 10.20 BTU /SEC for the assuned 40,000 MWD /MTU average l
dischargo burn-up.
If an irradiation time of 10 years was assuned, the corresponding decay heat rate predicted by j
APCSB 9-2 is 10.49 BTU /SEC which is still less than the
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value used in the rack design calculations. This value also a
i bwnds the decay heat generated by the seven lead test assenb11es with an expected burn-up of 44,000 MWD /MTU.
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Attechnent A 4
Pegs 3 of 7
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l 450.2 QUESTION:
Please provide a discussion of the apparent discrepancy between
. Technical Specification 4.10.C which indicates that the spent fuel pool water depth shall provide at least an 8 ft. water cover over the stored spent fuel and the stail's assumption of a DF_of 100, corresponding to a 23 ft, water cover,' in its re' fueling accident evaluation in its August 11, 1972 SER. Provide the actual present water depth over the spent fuel.
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RESPONSE
I The intent of the Technical Specification is to provide adequate i-water coverage for cooling and shielding at all times, including
_during fuel movement. Interlocks are provided on the refueling platform to prevent the fuel from being raised to a point where I
there would be less than 8h' ft. of water over the top of active fuel. With the water.at elevation 233' (its not; mal operating level),
j 23 ft. of water. is maintained above fuel stored in the spent' fuel storage racks and 8 ft.. of water is maintained above the top of active _ fuel while it is in transfer.
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Additionally, the elevation of the spent fuel pool' overflow to the skimmer surge tanks is such that 23.ft. of water cover is maintained.
There are no suction _ paths in the Espent fuel pool at any lower
. elevation.
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I Attcche:nt A
.Prg2 4 of 7 450.3 QUESTION:
Discuss the anticipated variations in water level of the spent fuel Pool (s) during and following the reracking procedures.
RESPONSE
c It is not planned or anticipated that the spent fuel pool water level will vary during and following the reracking procedures. The design
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of the spent fuel pool overflow to the skimmer surge' tanks is such that a constant. pool water level is maintained.
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i Attichment'A
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Pcga 5 of 7 450.4.
QUESTION:
Discuss the variation of spent fuel pool water volatile iodine decontamination factor (DF) a) during and b) af ter. completion of the reracking procedures. Provide the basis for this assessment, justifying the DF's selected ~.
. RESPONSE:
The spent fuel pool water volatile iodine decontamination factor (DF) is not expected to vary during and after completion of the reracking procedures because pool water level is not expected to vary.
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Attaciunent A l'
Page 6 of 7 l*.
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450.5 QUESTION:
Discuss the effect of the variation of pool water DF on the consequences of fuel handling accidents previously evaluted in the PBAPS updated FSAR.
RESPONSE
Since pool water DF is not expected to vary, the consequences of fuel handling accidents previously evaluated in the PBAPS updated FSAR remain the same.
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AttcchmInt A-P gs 7 of 7 450.6 QUESTION:
Discuss the extent of any'present spent fuel pool water loss through leakage. Provide information on any anticipated changes in leakage due to the presence of the new high density racks.
RESPONSE:.
The Peach Bottom spent fuel pool design includes a liner leakage detection system consisting of collection troughs behind and beneath the stainless steel liner. These troughs collect any liner leakage and direct it to an open-funnel liquid radwaste drain. This drain is' monitored periodically and has never exhibited any liner leakage.
We do not anticipate any changes in liner leakage due to the presence of the new high density spent-fuel racks.
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October, 1985 Docket Nos. 50-277 50-278 RESPONSES 'IO LETTER, J. F. STOLZ TO E. G. BAUER, JR.
SEPTEMBER 5, 1985 - REQUEST FOR ADDITIONAL INFORMATION PEACH BOTTOM A'IOMIC POWER STATION UNITS 2 AND 3 INSTALLATION OF NEW SPENT EUEL RACKS ATTACHMENT B e
Page 1 of 3 - Westinghouse Affidavit e
Page 2 of 3 - Written Response to Question 231.1 e
Page 3 of 3 - Figure 4.4 Storage Cell Dimensions J
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Attachment C Page 10 of 13 1
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7.
QUESTION:
l Did any mounting foot of any rack lift off the pool floor?
c.
If so, by how much?
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RESPONSE
The maximum lift off from the pool floor of a support pad is c.
.0129 inch. This was determined for the 9 x 14 rack in the 9 cell direction.
NOTE:
One response is provided to answer questions 7d, e, and f.
7.
QUESTION:
d.
In addition to sliding, provide values of the max'imum displace-ments at the top corners of the rack modules' considering all contributors to displacement?
How:.was the clearance space between two adjacent racks apportioned e.
for comparison to the maximum rack displacement?
f.
Did the dynamic rack displacement analysis provide for two adjacent racks to have out-of-phase movement?
G e
Attachment C Page 11 of 13 4
l RESPONSE: (to 7d, 7e, 7f continued) l The condition which produces the maximum fuel rack seismic response is all fuel racks filled with fuel. For this configuration the rack responses (sliding and structural deflection) will be in phase, thus the rack to rack gap is not affected. The major factor which produces the phase relationship for this condition is the hydrodvnea'
- cffect of the submerged structure.
However, due to variation of friction or for other than racks full of fuel, there may be a condition where one rack slides and the adjacent rack does not slide. For this condition the rack to rack gap will be reduced by the amount of one rack sliding, two racks structurally deflecting, and the thermal movement of the racks for the installed temperature to the maximum normal temperature. Since the structural displacements of the racks are out of phase or unrelated, the combined seismic displacements were obtained by the square root of the sum of the squares (SRSS) method. Table 1 shows the final calculation to obtain the maximum displacements at the tops and the bases of the racks.
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Attachment C, Pcg2 12 of 13' (Rasp:nta to 7d, 7a, 7f ccntinuid) i
),a Table 1 SSE Seismic + Maximum Normal Thermal SSE Seismic
+ Normal Thermal i
RACK RACK TOP BASE
'n 0.049 0.049 f
Max. Sliding Distance, p =.2 4s i
6 s = (.0098)S*
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Max. Structural Defl., p =.8 8
in 0.647 0.0 j
Total Displacement One Rack a = ds + f 6
in 0.696 0.049 SRSS Combined Displacement 2 Racks with o,,x in 0.950 0.049 Only 1 Sliding.d,,x " /d2 + j: 2 1
Max. Normal Thermal Displacement f
in 0.087 0.0P.?
T Max. Combined Thermal & Seismic Displacements 2I in 1.037 0.136 b " [T
+O max Nominal Rack to Rack Gap
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C in 1.68, 1.03 6.'
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- This accounts for 5 OBE events i
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Attachment C Page 13 of 13
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8.
QUESTION:
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On Page 4-23 of the submittal, the Licensee states that "the energy
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which produces lift-off was applied to the fuel rack module...."
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Please identify what energy was applied and describe the nature and methods of the analysis.
RESPONSE
The nonlinear time history analysis determined the maximum vertical lift-off of the support pads. Knowing the maximum pad lift-off, the maximum vertical lift of the fuel rack module center of gravity (CG) 7 can be determined. The energy that produces lift-off is obtained by multiplying the vertical lif t of the rack CG by the weight of the rack and fuel in the.wdel.
Since the time history analysis results are on a per cell basii, the total energy which produces lif t-of f for an entire fuel rack mod,tle is obtained by multiplying "the lift-off energy fur a single cell by the number of cells loaded with fuel.
For a rack module loaded with a particular number of fuel assemblies, the vertical lif t of the CG can be obtained since the lif t-of f energy is known and the weight of the rack and fuel is known (CG lift = Energy /
Weight). Once the actual CG vertical lift i~s known, the factor of safety against overturning is calculated by ratioing the movement of the Cd required for the rack to overturn co the actual CG vertical lift. For the Peach Bottom fuel racks, the minimum factor of safety against overturning is calculated to be 73 which is much greater than that required by Section 3.8.5.II. of the Standard Review Plan.
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