ML13317A307
| ML13317A307 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/01/1982 |
| From: | Krieger R Southern California Edison Co |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13317A309 | List: |
| References | |
| TASK-03-04.C, TASK-09-01, TASK-3-4.C, TASK-9-1, TASK-RR NUDOCS 8209030258 | |
| Download: ML13317A307 (4) | |
Text
Southern California Edison Company P. 0.
BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 September 1, 1982 Director, Office of Nuclear Reactor Regulation Attention:
D. M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 SEP Topics:
IX-1, Fuel Storage III-4.C Internally Generated Missiles San Onofre Nuclear Generating Station Unit 1
References:
A. Letter from R. W. Krieger, SCE, to D. M. Crutchfield, NRC, dated April 29, 1982 B. Letter from D. M. Crutchfield, NRC, to R. Dietch, SCE, dated July 16, 1982 The Reference A letter forwarded our draft Safety Assessment of SEP Topic IX-1, Fuel Storage. The Reference B letter requested additional information on this topic as well as SEP Topic III-4.C, Internally Generated Missiles. Enclosure 1 contains additional information concerning new and spent fuel storage at San Onofre 1. Enclosure 2 is a set of drawings as described in Enclosure 1. It should be noted that we are now in the process of verifying Keff for spent fuel storage and expect to forward our results by November 15, 1982.
The information requested on Topic III-4.C, Internally Generated Missiles was not available to be submitted with this letter, but should be submitted by September 30, 1982.
If you have any questions concerning this information please contact me.
Very truly yours, R. W. Kriege A,
1.bS Supervising Engineer San Onofre Unit 1 Licensing EnclosuresLa e
ol e209O3O258 820901 PDR ADOCK 05000206 P
PDR RESPONSES TO ADDITIONAL QUESTIONS SEP TOPIC IX-1, FUEL STORAGE Following are responses to specific questions on SEP Topic IX-1, Fuel Storage, as forwarded by letter dated July 16, 1982 from D. M. Crutchfield, NRC, to R. Dietch, SCE. For each question the request is restated and the response follows.
- 1. Request The licensee is requested to verify that a Keff equal to or less than 0.98 will be maintained with new fuel of the highest anticipated reactivity assuming optimum moderation, for example, foam, spray, small droplets or mist.
Include any information regarding the new fuel storage facility which would prevent inadvertent flooding (e.g., covers, drains, etc.).
Response
Due to the conservative design of the new fuel storage racks at San Onofre 1 it can be assured that the Keff of new fuel of the highest anticipated reactivity, assuming optimum moderation, will be maintained below 0.98.
As shown in SCE Drawing 568148, Fuel Storage Building, New Fuel Storage Racks (enclosed), the fuel is stored in two sets of racks, each containing two rows of fuel.
Keff is maintained as low as possible due to the wide spacing of the fuel assemblies. The closest approach of assemblies in the racks is 20-1/8 inches on each side and 2 feet 2 inches across (again see the plan view).
The racks are spaced 3 feet apart. These distances are much greater than the spent fuel storage racks (which has assemblies at 20-1/8 inches on all sides) which gives assurance that Keff will be maintained below 0.98. We expect this conclusion to have additional support when the Keff for the spent fuel pool is available (see No. 3 below).
Inadvertent flooding of the new fuel racks was described in our SAR submitted April 29, 1982. As described there, the design of the new fuel storage facility is such that inadvertent flooding is not a credible event.
- 2. Request The licensee is requested to verify that spent fuel storage racks are designed such that a fuel assembly cannot be inserted anywhere other than in a design location.
Response
The design of the spent fuel racks is such that a fuel assembly cannot be inserted anywhere other than in design locations. As detailed on SCE drawing 568147, Fuel Storage Building, Spent Fuel Storage Racks (enclosed), there are cross bars spanning the spaces between the fuel locations which physically prevent a fuel assembly from being inserted.
The "plan--top grid" portion of the drawing shows a portion of the bars in the upper left corner.
-2
- 3. Request The licensee is requested to verify that for the spent fuel pool a Keff equal to or less than 0.95 will be maintained when the storage racks are fully loaded and flooded with non-borated water.
Response
Section 5.4 of the San Onofre 1 Technical Specifications states that the fuel storage facility be designed such that K is maintained at <0.9. We are now in the process of verifying this number for fully loaded racks flooded with non-borated water and in addition we are assuming coolant temperature ranging from normal through boiling. It is currently anticipated that a Keff of <0.95 will be verified by November 15, 1982. Results of the analysis will be submitted at that time.
- 4. Request The licensee stated in his submittal dated April 29, 1982 that the spent fuel pool temperature would be maintained below 1200F. The licensee did not indicate use of Branch Technical Position (BTP) ASB 9-2 for calculating the decay heat loads. Consequently, we are not sure how much conservatism is in the licensee's analysis. Therefore, provide the following information with the heat exchangers expected fouling factor and pluggage factor for the life of the plant:
- a. Maximum normal heat load and the pool temperature with the maximum normal heat load using the heat load based on BTP ASB 9-2;
- b. Maximum normal heat load and the pool temperature with the maximum normal heat load using the heat based on BTP ASB 9-2 and the worst single active failure. Provide a discussion of the failure and the operation of the remaining portion of the system;
- c. Maximum abnormal heat load and pool temperature resulting from a full core off-load 30 days following a refueling off-load (pool should be considered filled) using the BTP ASB 9-2; and
- d.
Given a loss of all spent fuel pool cooling provide the time to pool boiling for the maximum heat load and for the maximum abnormal heat load.
Response
An analysis has been performed of the spent fuel pool heat loads based on BTP ASB 9-2. The following assumptions were used in making the calculations:
- i.
90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> is the time required after shutdown to transfer the spent fuel into the pool.
This is a conservative assumption as a requirement that fuel not be moved for at least 148 hours0.00171 days <br />0.0411 hours <br />2.44709e-4 weeks <br />5.6314e-5 months <br /> after being subcritical is set forth in Technical Specification 3.8 (A.5).
-3 ii.
Residual heat release is based on a reactor operating time of 16,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />.
iii.
No heat loss through the walls is assumed.
The results of the calculations are as follows:
- a.
The maximum normal heat load is 2,364,240 Btu/hr.
The maximum normal pool temperature is 88.50F.
- b.
The maximum normal heat load assuming the worst single active failure would be the same as above. The maximum normal pool temperature assuming the worst single active failure would be pool boiling or 212 0F. However, this is based on a single active failure of the spent fuel pump. Normally, the pump can be repaired or replaced prior to any adverse affects. A spare pump is available on site and could be installed prior to attaining pool boiling conditions in the times indicated in (d) below.
- c.
The maximum abnormal heat load and pool temperature resulting from a full core off-load 30 days following a refueling off-load is 6,788, 740 Btu/hr. and 116 0F, respectively.
- d.
Given a loss of all spent fuel pool cooling, it would take approximately 136 hours0.00157 days <br />0.0378 hours <br />2.248677e-4 weeks <br />5.1748e-5 months <br /> to pool boiling for normal heat load and 47 hours5.439815e-4 days <br />0.0131 hours <br />7.771164e-5 weeks <br />1.78835e-5 months <br /> for the maximum abnormal heat load.
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