ML20002B093
| ML20002B093 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 12/05/1980 |
| From: | Dewitt R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML20002B087 | List: |
| References | |
| NUDOCS 8012090426 | |
| Download: ML20002B093 (5) | |
Text
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CONSUMERS POWER COMPANY Docket 50-155 Request for Change to the Technical Specifications License DPR-6 For the reasons hereinafter set forth, it is requested that the Technical Specifications contained in the Facility Operating License DPR-6, Docket 50-155, issued to Consumers Power Company on May 1, 1964, for the Big Rock Point Plant be changed as described in Section I below-I.
Changes Section 3.5.1 Revise to read as follows:
" Design Features Shall Be As Follows:
(a) Number of Sets of Spray Nozzles 2
(b) Capacity of Spray Sets at 100 Psid Nozzle Pressure (i)
Primary Spray Set, Gpm 146 (ii) Secondary Spray Set, Gpm 233 (c) System Actuation (i)
Primary Spray Set Automatic D-C Operated (ii) Secondary Spray Set Remote Manual A-C Operated (d) Signal Used To Actuate High Containment Sphere Pressure (c) Signal Trip Setting 5 2.2 Psig (f) Reserve Water Supply Lake Michigan" Section 11.3.3.4 Revise Specification A of the Containment Spray System Limiting Conditions for Operation to read as follows:
"A.
During power operation, both of the two containment spray systems shall be operable."
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2 Section 11.4.3.4 Delete Specification E of the Containment Spray System Surveillance Requirements.
Table 11.4.3.4 Change the High Enclosure Pressure Trip System Logic to read:
"1 of 2 taken twice."
Delete the time delay parameter and all associated Limiting Conditions for Operation and Surveillance Requirements.
- Also, delete footnote (b).
Bases:
(Containment Spray System)
Revise the Containment Spray System bases to read as follows:
"The Containment spray systems are provided to reduce pressure and temperature in the containment following a Loss of Coolant Accident (LOCA). They are initially supplied from the fire water system and later by the core spray recirculation system. They are not re-quired to be in service at reactor coolant temperatures of 212*F or below because the resultant LOCA pressure is not sufficient to l
pressurize the containment.
" Operation of only one system is sufficient to provide the renuired containment spray flow for containment temperature and presst:=
suppression following a LOCA. The primary containment spra set is automatically initiated. The secondary containment spray set may be manually initiated upon failure of the primary containment spray set.
"The operable status of these systems and components is demonstra-ted by periodic tests.
If a component is found to be inoperable, it will be possible in most cases to effect repairs and restore the system to full operability within a relatively short time.
If a single system becomes inoperable, a redundant system has been pro-vided which is capable of performing the intended function.
" Initiation of the containment spray system assures that contain-ment design pr<4sure will not be exceeded due to hydrogen genera-tion assuming the core spray systems do not function.
It has been conservatively calculated that the energy release following a com-plete core meltdown (assuming no containment spray systems or core spray systems operate) would bring the containment pressure to approximately the design value (27 psig) about 15 minutes after the postulated accident had occurred.
Subsequent LOCA analysis system modifications and regulations have li'ited H2 generati;n such that it is no longer significant and calculations show thr.c containment nu1280-0056a-43
H' 3
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l sprays are not required to prevent containment design pressures L
from being exceeded."
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References:
l 1.
Big Rock Point Plant - Final Hazards Summary Report (FHSR),
November 14, 1961, Docket'50-155, DPR-6, Sections 3.7, 5.9, 7.5.2, 13.4.2 and 13.6.2.2.
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2.
Consumers Power Company letter to the USAEC dated March 17 j
1966 - Additional Information in Support of Proposed Tech Spec Change No 8-(Docket 50-155, DPR-6).
l 3.
USAEC letter to Consumers Power Company dated April 14, 1966 -
Approved Tech Spec Change No 8 (Safety Evaluation Report).
II.
Discussion The above proposed Technical Specifications change is requested to allow l
implementation of plant modifications designed to mitigate the effects j
of steam pipe breaks.
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(
As a result of Licensee Event Report No 80-023, dated August 26, 1980, Consumers Power Company. undertook an investigation of possible plant modifications to minimize the potential for containment and vital equipment temperatures exceeding the design temperature of 235'F during steam pipe breaks. As a result of this investigation, the modifications described in the attached Appendix A are being implemented. Engineering design, procurement, and installation of the modifications are in progress at'this time to. permit a late December 1980 start-up from the current refueling outage. The modifications incorporate a prompt automatic containment spray system (herein called the primary containment spray) which is sized to permit coincident containment and core spray systems operation during a large break LOCA. A remote manual backup containment spray system (the secondary system) is also provided.
The secondary containment spray is sized such that its spurious actuation will not -prevent delivery of adequate core spray flow. The primary. spray is actuated on high' containment pressure of 5 2.2 psig.
Both systems provide spray water to the steam drum cavity as well as'to the rest of containment. Although not provided in the original design of the plant, steam-drum-cavity spray is necessary to assure that the vital equipment withi
't enclosure is not subjected to temperatures l
In excess of its de
'-rature.
Analyses of the containment response to a spectrum of steam' pipe breaks cre provided in Appendix B.
Based on'these analyses, it is concluded j
that the primary containment spray system will provide adequate cooling of the containment atmosphere to assure that containment and vital equipment' design temperatures are not exceeded. Except for the largest steam pipe-breaks, the containntat spray system maintains containment air temperatures below 235*F throughout the accident. For the large nu1280-0056a-43
4 steam pipe breaks, air temperatures within the steam drum cavity and possibly in the outer containment may exceed 235'F, but only for a brief period of time. The thermal capacity of the vital equipment is considered sufficient to assure its functionability for the time period required (less than two minutes following a large pipe break).
It should be noted that the vital equipment within the steam drum enclosure consists of the following: The primary core spray line flow transmitter (PT-2162); the primary core spray line valves (MO-7051, -7061); and, the main steam line isolation valve (MO-7050). The flow transmitter has been qualified (Ref 1) for an environment of 288*F and, therefore, will certainly remain functional following the large steam pipe break. The core spray valve and MSIV motors were qualified (Ref 1) by evaluation based on testing of a similar unit at 240 F, 43.7 psia, aad with tap water spray.
Because the source of water (the fire system) for the containment spray systems is the same as for the core spray systems, it was necessary to verify that sufficient spray water will be delivered to the core given the modified containment / core spray systems considering the spectrum of possible single failures. These analyses are provided in Appendix C.
The conclusion from these analyses is that adequate core spray flow (292 gpm from the core spray sparger or 296 gpm from the redundant spray nozzle) will be provided assuring the worst single failure for all pri-mary coolant pipe breaks.
It should be noted that these core spray flow requirements assure adequate core spray distribution as verified by actual full-scale model testing of the Big Rock Point core spray sparger and redundant nozzle.
For some very small steam pipe leaks, the containment ventilation system will prevent sufficient containment pressurization to cause automatic containment isolation and its resultant automatic primary containment spray system actuation. Therefore, analyses of necessary operator response times to assure timely containment spray are provided in Appendix D.
Based on these analyses, it is concluded that the operator would have at least 10 minutes in which to detect the leak and take appropriate corrective actions.
Symptoms associated with a steam pipe break and the rationale for the conclusion that the operator will respond in the time allowed are presented in Appendix E.
References:
1.
Consumers Power Company Environnental Qualification of Electrical Equipment Submittal, dated October 31. 1980, from D P Hoffman to D M Crutchfield.
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III. Conclusion Based on the foregoing, both the Big Rock Point Plant Review Committee and the Safety and Audit Review Board have reviewed these changes and find them acceptable.
CONSUMERS POWER COMPANY By 1
R B DeWitt, Vice President Nuclear Operations Sworn and subscribed to before me this 5th day of December 1980.
Linda K Carstens, Notary Public Jackson County, Michigan My commission expires June 10, 1981.
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