ML19347B530
| ML19347B530 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 09/23/1980 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 1-166, IEB-80-18, NUDOCS 8010150295 | |
| Download: ML19347B530 (4) | |
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C.',., TOLEDO i
- EDISON Docket No. 50-346 RoiAna P. Dna
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vuwnet N.A 4 M License No. NPF-3 14,3 m w a
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Serial No. 1-166 September 23, 1980 1
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Mr. James G. Keppler i
Regional Director, Region III
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Office of Inspection & Enforcement U.S. Nuclear Regulatory Commission
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799 Roosevelt Road Glen Ellyn, Illinois 60137 i
Dear Mr. Keppler:
This letter is in response to IE Bulletin 80-18, dated July 24, 1980
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(Log No. 1-398) as applicable to Davis-Besse Nuclear Power Station Unit 1 (DB-1).
This Bulletin relates to maintenance of adequate minimum j
recirculation flow for the High Pressure Injection Pumps. The attach-ment provides Toledo Edison response to the subject Bulletin.
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As requested in your letter, following is a break up of manpower expended in preparation / approval / distribution of this report:
Toledo Edison Nuclear Engineering Staff 35 Manhours i
Toledo Edison Licensing Staff 2 Manhours Toledo Edison DB-1 Station Staff 16 Manhours i
Toledo Edison Clerical Staff 19 Manhours Bechtel Engineering Staff 50 Manhours Bechtel Engineering Administration Staff 8 Manhours 4
j Becthel Non Engineering Staff 6 Manhours i
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Very truly yours, W
ff Attachment cc:
Mr. V. R. Stello, Jr., Director 4
NRC Office of Inspection & Enforcement Division of Reactor Operations Inspection Washington, D.C.
20555 NRC D-B 1 Resident Inspector bt a/1 THE TOLEOO EDISON COMPANY EOISON PLAZA 300 MADISON AVENUE TOLEDO, OHIO 43652 Q
5010150276
Docket No. 50-346 License No. NPF-3 Serial No. 1-166 September 23, 1980 TOLEDO EDISON COMPANY RESPONSE TO NRC IE BULLETIN 80-18 FOR DAVIS-BESSE NUCLEAR POWER STATION UNIT 1 i
Item 1 In a quantitative manner (perfc.m the calculations, outlined in the enclosure, for your p).nt), determine whether or not 4
j minimum cooling is provided to centrifugal pumps used for high pressure injection, for all conditions requiring CI, prior to satisfying SI termination criteria.
If a " minimum flow bypass" i
line is present which remains open during high pressure injec-tion, and if that line guarantees that minimum cooling flow will be provided to the pumps under such conditions, then no i
further calculations are required if all safety related analyses (Item 2.d below) assumed presence of the open line.
i Response The concern identified in the subject bulletin is not applicable j
to the Davis-Besse Nuclear Power Station Unit 1 (DB-1).
The centrifugal pumps used for High Pressure Injection (HPI) at DB-1 are equipped with a minimum recirculation line each, l
containing a restriction orifice. Whenever the HPI pumps are taking suction from the Borated Water Storage Tank (BWST),
1 this recirculation line will be open and will remain open providing adequate minimum flow recirculating to the BWST.
The valves in the recirculation lines will not close on Safety Injection (SI) initiation.
Refer to FSAR Figures 6-17 and 6-19 for flow diagrams of the Emergency Core Cooling System (ECCS).
If the BWST were pumped down to its low-low level setpoint and HPI termination criteria were not satisfied, the HPI pumps would be placed in the " piggy-back" mode of operation. This mode of operation is described in FSAR Seciion 6.3.1.4.
The HPI pumps would take suction from the outlet of the decay heat removal coolers to provide for containment vessel emergency sump water recirculation to the reactor core.
When this
" piggy-back" mode of operation is initiated, the plant operators will close the valves in the HPI pumps minimum flow recircula-tion lines. This will prevent pumping water from the contain-ment vessel to the BWST. During this mode of operation the HPI flow will be adequate to maintain pump cooling provided the Reactor Coolant System (RCS) pressure is less than 1750 psig.
Analysis has shown that when the HPI pumps are in the piggy-back mode (BWST it L..iew the low-low level setpoint), the HPI termination criteria will be satisfied prior to RCS repressur-ization to 1750 psig.
In addition, the plant operators will stop the HPI pumps prior to the pump flow rate decreasing to less than adequate minimum flow for pump cooling.
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O Docket No. 50-346 License No. NPF-3 Serial No. 1-166 September 23, 1980 This condition could only result following a small break in
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the primary system or a break in the primary system which is isolated. The HPI termination criteria are described in the plant operating procedures which are associated with this type of accident.
See " Evaluation of Transient Behavior and Small Reactor Coolant System Breaks in the 177 Fuel Assembly Plant, Volume 3, Revision 1, transmitted to the NRC through Serial No. 506 dated May 22, 1979.
For a further discussion of small breaks resulting in reactor coolant system repressurization, see NRC document NUREG-0565, " Generic Evaluation of Small Break Loss-of-Coolant Accident Behavior in Babcock & Wilcox j
Designed 177-FA Operating Plants", Sections 4.1.2.3.4 and i
4.1.2.5.
It is emphasized that the HPI pumps minimum flow j
recirculation lines are only isolated when the BWST has been pumped down to its low-low level setpoint and t'ie HPI pumps are in the " piggy-back" mode of operation. After isolation of the recirculation lines, should a low minimum flow condition occur, the operators will shut off the HPI pumps. Following a secondary side line rupture and SI actuation (with no break in j
the Reactor Coolant System), the HPI pumps minimum flow recir-culation lines will always remain open. The BWST cannot be pumped down to its low-low level setpoint following a secondary side line rupture.
The HPI pump flow rates used in all safety-related analysis have taken into account the recirculation flow path, as presently designed and installed.
Based on the above, it is concluded that at DB-1 the HPI pumps will have adequate cooling flow for all conditions requiring safety injection prior to satisfying SI termination criteria.
Item 2 If availability of minimum cooling flow for the CCPs is not assured for all conditions by the calculations in Item 1:
a.
Make modifications to equipment and/or procedures, such as those suggested in the enclosure, to insure availability of adequate minimum flow under all conditions.
If modifi-cations are made as described in the attachment for 2
interim modification II, verify that the Volume Control Tank Relief Valve is operable and will actuate at its design setpoint.
b.
Justify that any manual actions necessary to assure adequate minimum flow for any transient or accident requiring SI can and will be accomplished in the time necessary.
Docket No. 50-346 License No. NPF-3 Serial No. 1-166 September 23, 1980 Verify that any manipulations required (valve opening or c.
closing, along with the instrumentation necessary to indicate need for the action or accomplishment of the action, etc.) can be accomplished without offsite power available.
d.
Justify that flow available from the CCPs with the modifi-cations in place will be sufficient to justify continued applicability of any safety-related analyses which take credit for flow from the CCPs (LOCA, IIELB, etc. ).
l Justify that all Technical Specifications based on the e.
Item 2.d analyses remain valid.
Response Not applicable.
See response L.
Item 1 above.
Item 3 Provide the results of calculations performed under Item 1, and describe any modifications made as a result of Item 2 (include the justifications requested).
Response Not applicable.
See response to Item 1 above.
bj x/1-3 l