ML20216E230
| ML20216E230 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 06/24/1987 |
| From: | Brey H PUBLIC SERVICE CO. OF COLORADO |
| To: | Calvo J NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), Office of Nuclear Reactor Regulation |
| References | |
| P-87236, TAC-63576, NUDOCS 8706300661 | |
| Download: ML20216E230 (9) | |
Text
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h Public Service ~
- =;a 2420 W. 26th Avenue, Suite 1000, Denver, Colorado 80211 J
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i June 24, 1987 j
Fort St. Vrain Unit No. 1 P-87236 U. S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 4
Attention: Mr. Jose A. Calvo Director, Project Directorate IV Docket No.
50-267
SUBJECT:
Additional Information Concerning Analysis of Firewater Cooldown for 82% Power Operation
REFERENCE:
1)
PSC Letter, Williams to Berkow, dated January 15, 1987 (P-87002)
Dear Mr. Calvo:
In a telephone conversation on June 22, 1987, between the NRC's Mr.
Ken Heitner and various PSC personnel, PSC was asked to address the following questioris relating to the Technical Specification changes proposed in Reference 1:
1.
Can the redundant Safe Shutdown Cooling flow paths, consisting of the preferred mode with firewater supplied via the emergency condensate header and the backup mode with firewater supplied via the emergency feedwater header, withstand a single active failure and still provide adequate heat removal after reactor operation at power levels up to 82%?
PSC should also submit the results of an explicit analysis to demonstrate if the original Class I firewater flow path can accommodate a single active failure in the new Class I firewater flow path when the required EES pre-cooling times and the long term cooling are accounted for.
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8706300661 870624 PDR ADOCK 05000267
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P-87236 Page 2 June 24, 1987 2.
What instrumentation does PSC rely on to monitor helium circulator speed and steam generator EES outlet conditions during Safe Shutdown Cooling? Describe controls which PSC applies to this. instrumentation.
3.
Have operating procedures been prepared for those accidents which rely upon Safe Shutdown Cooling for decay heat removal and for fires which utilize the Appendix R shutdown cooldown model s? Have the operators been trained to follow these procedures?
PSC's responses to these questions are as follows.
Single Active Failures The emergency condensate header and the emergency feadwater header (EFW header) are the redundant flow paths used to supply firewater to a steam generator EES section and to an emergency water booster pump, which in turn provides motive-power to a circulator, for Safe Shutdown Cooling.
Any single active failure in either of these redundant flow paths can be compensated for quickly by manual actions or by utilizing the redundant flow path.
The emergency condensate header is the preferred firewater supply path for Safe Shutdown Cooling, as discussed ~ fn Attachment 4 of Reference 1,
since it has higher flow capability and can be aligned to the firewater system more expeditiously. The EFW header is the redundant firewater supply path for Safe Shutdown Cooling, which would be utilized in the event the emergency condensate header were not available.
Both are seismically and environmenta'ly qualified flow paths, and are protected from tornado damage.
Technical Specification LC0 4.2.2 requires both headers to be operable to supply the helium circulator water turbine drives for helium circulator operability.
Proposed revisions to LC0 4.3.1 (Reference
- 1) require that both steam generator EES sections be capable of receiving water from both the emergency condensate and EFW headers.
LC0 4.3.4 states "The reactor shall not be operated at power unless the emergency condensate header and the eme gency feedwater header are operable".
There are alternate means of supplying firewater to the emergency condensate header.
Firewater can be supplied directly to the emergency-condensate header through the newly installed line 6"L-45276, off the discharge of the two firewater pumps, by o Engineering Evaluation EE-EQ-0023 (Rev B)pening
- HV-4518 and HV-4519.
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P-87236 Page 3 June 24, 1987 includes the time line analysis which demonstrates that Safe Shutdown Cooling can be established, with firewater supplied to the emergency condensate header via 6"L-45276, in less than 90 minutes.
Firewater can also be supplied to the emergency condensate header via the firewater ring header.
Firewater can be supplied to the EFW header via V-45223 from the firewater ring header. Alignment of firewater to one of the EES sections via this flow path requires depressurization of the EFW header to atmospheric pressure, removal of the blind insert at the firewater /EFW header cross - connect and replacement with a through l
insert.
Engineering Evaluation EE-EQ-0055 (Rev A) includes the time line analysis which demonstrates that Safe Shutdown Cooling can be established with the EFW header in less than 90 minutes.
PSC has confirmed that these redundant flow paths can withstand any single active failure and adequately support Safe Shutdown Cooling from reactor power levels up to and including 83.2%.
The new Class I firewater flow path consists of 6"L-45276 and its in-line isolation valves (HV-4518 and HV-4519) in the firewater supply path to the emergency condensate header and the new main steam six inch vent lines for each loop. 6"L-22555 is the loop 1 main steam vent line which has two in-line isolation valves, HV-22819 and HV-22821, 6"L-22557 is the loop 2 main steam vent line which also has two in-line isolation valves, HV-22820 and HV-22822. All six of the above noted valves in the new Class I firewater flow path are manually operable valves.
While these valves have provisions for remote operation by motor operators, the motor operators are currently not electrically connected so the valves must be local-manually positioned. Therefore, these six valves are not presently vulnerable to active failure.
When the motor operators for these valves are electrically connected and placed in service in the future, each of these valves could be the subject of a single active failure in the motor operator. This single active failure could be compensated for by use of each valve's local manual operator to override the motor operator and position the valve.
A conservative EES pre-cooling time of 14 minutes (Proto Power Calculation No. 82-10, Rev, "EES Flooding Time With Firewater") was considered in the time line analyses for Safe Shutdown Cooling with firewater supplied by the emergency condensate header (EE-EQ-0023, Rev B) and by the emergency feedwater header (EE-EQ-0055, Rev A).
Based on this discussion, it is concluded that the original Class 1 firewater flow path can accommodate a single active failure in the new Class 1 firewater flow path when the required EES pre-cooling times and the long term cooling are accounted for.
P-87236 Page 4 June 24, 1987 Instrumentation to Monitor Safe Shutdown Cooling The instrumentation identified in Attachment I will be available post-accident to monitor and control Safe Shutdown Cooling.
As a result of analyses performed by PSC, helium circulator speed and steam generator outlet temperature and pressure are the primary parameters used to control the primary-to-secondary heat removal rate and therefore to control shutdown cooling.
PSC letters Warembourg to
- Johnson, dated 2/28/85 (P-85065) and Warembourg to Berkow, dated 7/14/86 (P-86460), define the post-accident monitoring categories identified in the following attachment. The following indicators are specifically used during the post-accident period to either monitor or control the Safe Shutdown Ccoling mode of operation.
1.
Primary coolant heat removal rate is controlled by monitoring helium circulator speed indicators SI-2109/2110/2115/2116.
This indication is available during the entire post-accident period following restoration of forced circulation cooling.
2.
Steam generator outlet temperature and pressure monitoring:
Prior to controlling cooldown using local high-accuracy temperature and pressure instruments, steam generator pressure and temperatures are monitored using installed instrumentation (TE-22121/22122; PI-22129-1/22130-1) which h seismically and environmentally qualified and can be monitored from remote locations, including the Control Room I
and the Technical Support Center (TSC).
These temperature / pressure indicators are located downstream of 4
the point at which the main steam six inch vent lines tie into the main steam headers for each loop, and would therefore not provide useful information after Safe Shutdown Cooling is established and secondary coolant exits one of the six inch vent lines to atmosphere.
3.
Control of Safe Shutdown Cooling:
Following steam generator depressurization and cooldown, local, high-accuracy pressure and temperature instruments (TE-22823/22824; PI-22129-2/22130-2) are placed in service to enable operators to monitor and control steam generator temperature and pressure to maintain the desired secondary-side heat removal rate.
In an emergency, and as required when using the emergency feedwater header, temperature indicators located on the outlet of each individual steam generator EES module (TE-2225-1 thru -6; TE-2226-1 thru -6) may be monitored to determine the outlet temperature of each steam generator module.
P-87236 Page 5 June 24,-1987 4.
Steam generator inlet temperature and pressure monitoring:
Prior to and during shutdown cooling, steam generator inlet flow (FT-2205/2206) and temperature (TE-2205/2206) indication are monitored to ensure adequate flow and heat removal rate.
Additionally, local pressure gauge PI-31204 is checked prior to initiation of cooling water flow to ensure the availability of the emergency condensate header.
Procedure Preparation and Operator Training The following procedures have recently been prepared to direct the operators to take the necessary actions to establish Safe Shutdown Cooling following a HELB, Design Basis Earthquake or Maximum Tornado and to establish adequate forced circulation cooling utilizing Appendix R Fire Protection Shutdown /Cooldown Train A or Train B for postulated fires outside the congested cable areas:
SSC-01 Restoration of Power to Essential 480 Volt Buses SSC-02 SLRDIS Reset Procedure SSC-03 Recovering from a Non-Congested Cable Area Fire Resulting in an Interruption of Forced Circulation SSC-04 Recovery from SLRDIS SSC-05 Design Basis Earthquake / Maximum Tornado Recovery The applicable emergency procedures for these events have been appropriately revised to refer to the above noted procedures' which detail the actions necessary to establish Safe Shutdown Cooling and Appendix R Fire Protection shutdown cooling.
These detailed procedures and their accompanying 10 CFR 50.59 Safety Evaluations have been approved by FSV's Plant Operations Review Committee.
With the exception of two Auxiliary Tenders presently on vacation, all FSV operators have completed initial training on these procedures. These two individuals will complete this training shortly after returning from vacation.
Ongoing training on these procedures will be conducted through the operator requalification training program.
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P-87236 Page 6 June 24, 1987 If you have any questions, please contact Mr. M. H. Holmes at (303)-
480-6960.
Very truly yours, H. L. Brey, Manager Nuclear Licensing and Fuels Division HLB /JRJ:bac Enclosure cc: Regional Administrator, Region IV Attention: Mr. J. E. Galiardo, Chief Reactor Projects Branch Mr. R. E. Farrell Senior Resident Inspector Fort St. Vrain
ATTACHMENT 1 to P-87236 POST-ACCIDENT TNSTRUMENTATION AVAILABLE FOR MONITORING SAFE SHUTDOWN COOLING L-(1) Helium Circulator speed indication:
Purpose:
Primary indicator of primary heat removal rate Instruments: SE-2109-1/2210-1/2215-1/2216-1 Indication Range: 0-12000 RPM-Indication Accuracy: +180 RPM Indication Location: Control Room, TSC, FCP Calibration Frequency:
12 mos.
RG 1.97 Category: 1 (2) Steam Generator outlet temperature:
Purpose:
Monitor post-accident Steam Generator outlet temperature Instruments: TE-22121/22122 Indication Range:
0-1200 degrees F Indication Accuracy: +18 degrees F Indication Location: Control Room, TSC, FCP Calibration Frequency:
18 mos.
RG 1.97 Category: 2
Purpose:
Control Steam Generator outlet temperature during Safe Shutdown Cooling Instruments: TE-22823/22824 Indication Range: 50-550 degrees F Indication Accuracy:
+8 degrees F Indication Location: Cocal only, Reactor Bldg, (mechanical indicator)
Calibration Frequency:
12 mos.
RG 1.97 Category:
None established at present
Purpose:
Control Steam Generator Module outlet temperature during cooldown using Emergency Feedwater Header Instruments: TE-2225-1 thru -6; TE-2226-1 thru -6 Indication Range:
0-1100 degrees F Indication Accuracy:
+6 degrees F Indication Location: fontrol Room, Auxiliary Electric Equipment Room Calibration Frequency:
18 mos.
RG 1.97 Category:
None Established at present ATTACHMENT 1 to P-87236 POST-ACCIDENT INSTRUMENTAT10N AVAILABLE FOR MONITORING SAFE SHUTDOWN COOLING l
(3) Steam Generator outlet pressure:
Purpose:
Monitor Steam Generator pressure prior to commencing cooldown Instruments:
PT-22129-1/22130-1
. Indication Range: 0-3000 psig Indication Accuracy:
+45 psi i
Indication Location: Control. Room, TSC, FCP Calibration Frequency:
24 mos.
RG 1.97 Category: 2 l
Purpose:
-Control Steam Generator backpressure during Safe Shutdown Cooling Instruments:. PI-22129 2/22130-2 Indication Range: 300 psig Indication Accuracy:
+3.2 psi l
Indication Location: l'ocal only, Turbine Bldg, (mechanical-indicator) i Calibration Frequency:
12 mos.
RG 1.97 Category:
None established at present (4) Steam Generator cooling water flow:
Purpose:
Verify cooling water supply to Steam Generators during Safe
' Shutdown Cooling Instruments:
FT-2205/2206 Indication Range: 0-1.25 Mlb/hr Indication Accuracy:
+6250 lb/ hour-Indication Location: Control Room, TSC, FCP 1
Calibration Frequency: 24 mos.
RG 1.97 Category:
2
Purpose:
Monitor Steam Generator water inlet temperature during Safe Shutdown Cooling Instruments: TE-2205/2206 Indication Range: 0-500 degrees F Indication Accuracy:
+7.5 degrees F Indication Location: Control Room, TSC, FCP Calibration Frequency:
36 mos.
RG 1.97 Category: 3 !
ATTACHMENT 1 to P-87236-i POST-ACCfDENT INSTRUMENTAT10N
'AVAILABLE FOR MONITORING SAFE SHUTDOWN COOLING t:
_ (5). Firewater Supply Flowpath
Purpose:
Verify availability of the Emergency Condensate Header Instruments: PI-31204 Indication Range: 0-1000 psig Indication Accuracy:
+5 psi Indication Location: Cocal only, Turbine Bldg, (mechanical indicator)
Calibration Frequency:
12 mos.
RG 1.97 Category:
None established at present-i a.
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