ML20215L351
| ML20215L351 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 10/24/1986 |
| From: | DETROIT EDISON CO. |
| To: | |
| Shared Package | |
| ML20215L337 | List: |
| References | |
| NUDOCS 8610280588 | |
| Download: ML20215L351 (20) | |
Text
I Ms. Elinor G. Adensam Enclosure to VP-86-0132 Page 1 Backcround/Discunign The OPERABILITY of the control room emergency filtration system ensures that (1) the ambient air temperature does not exceed the allowable temperature for continuous duty rating for the equipment and instrumentation cooled by this system and (2) the control room will remain habitable for operations personnel during and following all design basis accident conditions.
Technical Specification 4.7.2.o.2 currently requires, at least once per 18 months the control room emergency filtration system shall be demonstrated OPERABLE by verifying that the system will automatically switch to its recirculation mode of operation on each of the following actuation test signals:
a) Control center inlet radiation monitor b) Reactor Building ventilation exhaust radiation monitor c) Radwaste Building ventilation exhaust radiation monitor d) Turbine Building ventilation exhaust radiation monitor e) Fuel pool ventilation exhaust radiation monitor f) Low reactor water level g) Uigh Drywell pressure This surveillance verifies that, on any one of these recirculation mode test actuation test signals, the system automatically switches to its recirculation mode of operation, the isolation dampers close within 5 seconds and the control room is maintained at a positive pressure of at least 0.125 inch water gauge relative to the outside atmosphere during system operation at a flow rate less than or equal to 1800 cfm through the emergency makeup air filter.
In addition to Technical Specification 4.7.2.e.2, the radwaste building and turbine building ventilation exhausts are each continuously monitored with their own
- radiation monitor as required in Technical Specification 3.3.7.12, " Radioactive Gaseous Effluent Monitoring Instrumentation". A trip of either of these radiation monitors places the Control Room IIVAC System into the recirculation mode and isolates the respective building-ventilation exhaust effluent release pathway.
I 8610280588 861024 PDR ADOCK 05000341 P PDR
Ms. Elinor G. Adensam Enclosure to VP-86-0132 Fage 2 These radiation monitor trip / alarm setpoints are determined and adjusted in accordance with the methodology and parameters of the Fermi 2 Offsite Dose Calculation Manual (ODCM) to implement limits on radioactivity in effluents to unrestricted areas as required by 10CFR20 paragraph 20.106.
In the past, hardware and software failures have occurred in the radwaste building ventilation exhaust radiation monitor, resulting in placing the Control Room HVAC in a recirculation mode. These events have been previously reported and described in Licensee Event Reports (LERs) (i.e.86-001, 86-015,86-023, 86-019, and 86-036).' In addition to identifying monitoring system deficiencies, subsequent investigation of these events has revealed that the related design basis and technical specification for the Engineered Safety Features (ESF) actuation are not necessary to meet GDC 19 requirements.
The monitoring system deficiencies have been corrected, which should minimize recurrences. However, ESP actuations will continue if (1) as yet unidentified monitor failure modes should appear, or (2) monitor trip / alarm setpoints are reached as a result of turbine building or radwaste building ventilation exhaust radioactive effluents.
A re-evaluation of this logic arrangement indicates that two of the above identified logic circuits, specifically the radwaste and turbine building ventilation monitors,are neither required nor desirable for causing the CCHVAC to enter the recirculation mode. These logic trips are not necessary because the tripping of either the turbine building or radwaste building exhaust ventilation radiation monitors will also result in the trip and isolation of the HVAC systems for the affected building. These actions will terminate any release of radioactivity in progress before a control room habitability consideration arises.
Additionally, in the event of a situation where the radionuclide concentration in the air supply to the CCHVAC rises to a level which could adversely affect control room habitability, including failure of the described radweste and turbine building HVAC trip functions, the control center inlet radiation monitor would cause the CCHVAC to trip into its recirculation mode. The remaining trip functions; reactor building ventilation exhaust radiation monitor, fuel pool ventilation exhaust radiation monitor, low reactor water level and high drywell pressure will be retained based
,' -Ms. Elinor G. Adensam Enclosure to VP-86-0132 Page 3 on the " Defense in Depth" approach, in that an alarm signal in anyone or all of these channels could occur in anticipation of a reactor or fuel handling accident.
Maintaining the radwaste and turbine buildings exhaust radiation monitor trip of the CCHVAC logic is considered undesirable because of the likelihood that spurious trips or maloperation of those radiation monitors will result in unnecessary challenges to the CCHVAC, which is an Engineered Safety Feature. Such unnecessary challenges reduce the reliability of this Engineered Safety Feature for response to valid initiations.
The proposed technical specification will eliminate the raduaste and turbine building monitors. The proposed change is included at the end of this enclosure.
Design Basis The existing design of the Control Center Heating, Ventilation and Air Conditioning System (CCHVAC) provides for logic trips which cause the system to automatically switch from its normal mode of operation into the recirculation mode of operation when any of the following logic circuits are tripped:
a) Control center inlet radiation monitor, b) Reactor Building ventilation exhaust radiation monitor c) Radwaste Building ventilation exhaust radiation monitor d) Turbine Building ventilation exhaust radiation monitor l e) Fuel pool ventilation exhaust radiation monitor l f) Low reactor water level g) High Drywell pressure The ir. tart of this logic arrangement is to ensure that j the con:tol room habitability requirements of GDC 19 of 10CFR50, Appendix A are met for post accident conditions. Fermi 2 compliance with GDC 19 is described in FSAR Section 3.1.2.2.10.
l The Fermi 2 FSAR Section 6.4.1 states that the total l dose to main control room personnel is the sum of the dose received while occupying the control center and the
! dose received during ingress-egress at shift changes.
l Doses received while in the main control room are due to l the radiation that penetrates the biological shielding and to the isotopes that enter the control center through the ventilation system or through the opening and closing of doors. Source terms and ind iv idu al
.' , Ms. Elinor G. Adensam Enclosure to VP-86-0132 Page 4 contributions of total dose are given in the Fermi 2 FSAR Chapter 15.
At Fermi 2 there is sufficient radiation shielding and air filtration provided to ensure that radiation exposures of the main control room personnel do not exceed 5 rem whole-body (GDC-19 limits) or its equivalent to any part of the body, for the duration of any DBA.
In calculating control conter personnel doses, various assumptions were made, including FSAR item 6.4.1.1.1.g which states:
" Radiation monitors in the reactor / auxiliary (i.e., fuel pool ventilation exhaust duc ting) , turbine and radwaste buildings detect airborne radiation concentrations above those specified in the Fermi 2 Technical Specifications and cause the control center air conditioning system to automatically switch to its emergency mode of operation."
The Fermi 2 CCHVAC System is designed with two independent control center inlet radiation monitors that also monitor the air from various areas within the plant and place the control center in recirculation (emergency mode) operation once radiation concentrations reach the technical specifications limit. Two pathways for radiation travel is through the turbine building and the radwaste building. Upon approval of this proposed technical specification change, the radiation monitor for either building will isolate its respective bu ild ing , however, it will not initiate a CCHVAC actuation and place the control center in an recirculation mode. In the event that the appropriate turbine /radwaste building monitors do not isolate themselves, then the control center inlet radiation monitors will isolate the control center upon detecting high radiation and will initiate the CCHVAC recirculation mode (emergency mode). Although the accumption in the Fermi 2 FSAR Section 6.4.1.1.1.g says that the turbine and radwaste buildings will initiate CCHVAC recirculation, deleting these two actions and taking credi* for the control center inlet r ad iation monitors does not invalidate nor change any of the Safety Analysis.
Uc will still have isolation of the turbine or radwaste buildings by their respective radiation monitors and before the radiation levels in the control center l
Ms. Elinor G. Adensam Enclosure to VP-86-0132 t Page 5 reaches their Technical Specification limits or Design Limits (FSAR Chapter 15.1) the CCHVAC will be put in recirculation by the control center inlet r ad iation monitors. There are two of these radiation monitors in
, order to meet the " Single Failure" criteria.
In reviewing the Fermi 2 FSAR (Sections 3.1.2.2.10 "GDC-19 Main Control Room", 6.4 " Control Room Habitability", 7.5 " Safety-related and Power Generation Display Instrumentation", 9.4 " Air Conditioning, Heating, Cooling and Ventilation Systems", 12.1 g " Shield ing " , and " Chapter 15" Accident Analysis) ,
Regulator Guide 1.52 " Design, Testing and Maintenance Criteria for Post Accident Engineered-Safety Features Atmosphere Cleanup System Air Filteration and Absortion Units of Light-Water-cooled Nuclear Power Plants" and GDC 19, we conclude that this change does not change any safety-systems or analysis. Therefore,the OPERABILITY of this system, in conjunction with control room design provisions, is based on limiting the radiation exposure to personnel occupying the control room to 5 rem or less whole body, or its equivalent. This limitation is consistent with the requirements of General Design Criterion 19 of Appendix A, 10CFR Part 50.
SAFETY EVALUATION In accordance with 10CFR50.59, Detroit Edison has reviewed the attached proposed technical specification and has concluded that there is no unreviewed safety question.
- 1) Is the probability of occurrence or the consequences of an accident or malfunction of equipment important to safety previously l evaluated in safety analysis report increased?
No. Operation of Fermi 2 in accordance with j the proposed technical specification will not involve an increase in the probability of occurrence or consequence of an accident j previously evaluated. This modification of the CCHVAC trip logic interlocks does not l change any of the parameters utilized in any
- previous accident analysis. The radwaste
' and turbine building vont exhaust fans and dampers will continue to isolate their respective areas upon reaching their i radiation monitor setpoints, however, the
- emergency makeup isolation mode of the l
I - .- -
,' ," Ms. Elinor G. Adensam Enclosure to VP-86-0132 Page 6 CCUVAC will no longer be initiated. The isolation of these vont exhaust paths will block their effluents from entering the CCHVAC makeup air inlet. In addition, the control room has two independent inlet radiation monitors that will place the CCHVAC in a recirculation mode if any effluents are detected.
- 2) Is there a possibility for an accident or malfunction of a different type than evaluated previously in the safety analysis report being created?
No. Operation of Fermi 2 in accordance with the proposed technical specification will not create the possibility of a new or different kind of accident from any accident previously evaluated. All the building effluent paths have the same monitoring and isolating features as in the original design. No new or dif ferent accident possibilities are created because the basis for the isolation of all the individual building vent exhaust paths remains unchanged.
- 3) Is the margin of safety as defined in the basis for any Technical Specification reduced?
l No. Operation of Fermi 2 in accordance with the proposed technical specification will not involve a significant r ed uct ion in the margin of safety since there is no change to the setpoints, design bases or in the response time of effluent monitors and isolation circuits. The radwaste and turbine building ef fluent paths will continue to be monitored for radiation and tripped closed as designed. The control center makeup air radiation monitor will continue to monitor the incoming makeup air j and isolate CCHVAC upon nonsing high radiation (Reference Bases Section l 3/4.7.2). The reactor building vent exhaust, fuel pool vent exhaust and the north and south control center
Hs. Elinor G. Adensam Enclosure to VP-86-0132 Page 7 cmergency air supply radiation monitoring channels will continue to initiate the recirculation mode of the CCHVAC.
In addition, the operator will receive annunciator indication of high radiation from the radwaste building vent exhaust, turbine building vent e::haust or the control center area radiation monitor and can manually isolate the control room in the unlikely circumstance that such actions would become necessary. Sufficient redundancy for isolation of the CCHVAC exists without the need for automatic isolation from the radwaste or turbine building monitors.
Eignificant Hazards Consideration In accordance with 10CFR50.92, Detroit Edison reviewed the attached proposed technical specification and has concluded that it does not involve a significant hazards consideration. The basis for this conclusion is that the three criteria of 10CFR50.92(c) are not compromised, a conclusion of which is supported by our determination made pursuant to 10CFR50.59 and which is discussed
. below:
(
- 1) The proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated. This modification would not l affect the ability to isolate the control room and all associated monitors would still provide isolation of their appropriate areas l thus still performing their intended safety function.
- 2) The proposed change does not create the
- probability of a new or different kind of l accident f rom any previously evaluated.
Since the monitors will still perform their intended safety functions and the monitors l have not been changed, the above statement is true.
- 3) The proposed change does not involve a significant reduction in safety margin. As shown in the Design Basis Section of this enclosure, Fermi control center personnel l
l
, ?!s. Elinor G. Adensam Enclosure to VP-86-0132 Page 8 will be within the GDC 19 guidelines of 5 Rem (whole body).
EfiVIROfU1EITI'AL IMPACT Detroit Edison has reviewed the proposed technical specification against the criteria of 10CFR50.22 for environmental considerations. As shown above, the proposed change concerns the deletion of the radwaste building and turbine building exhaust ventilation monitors to isolate their respective areas and not to place the Control Center HVAC System in recirculation mode since this action is handled by the control center inlet radiation monitor. This does not involve a significant hazards consideration, nor increase the types and amounts of effluents that may be released offsite, significantly increase individual or cumulative occupational radiation exposures.
Based on the foregoing, Detroit Edison concludes that the proposed technical specification does meet the i
criteria given in 10CFR51.22 (c) (9) for a categorical exclusion from the requirement for an Environmental Impact Statement.
Conclusion Based on the evaluations above: (1) there is reasonable assurance that the Heal th and Safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's Regulations and this proposed Amendment will not be inimical to the common defense and cocurity or to the Health and Safety of the public.
As previously stated, this proposed technical specification will not detract from the safety of Fermi 2 because this proposed change does not change any of the safety analysis, does not degrade any plant safety systems or alter any operator operations.
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PLANT SYSTEMS 3 SURVEILLANCE REQUIREMENTS (Continued) positive pressure of at least 0.125 inch water gauge relative to the outside atmosphere during system operation at a flow rate less than or equal to 1800 cfm through the emergency makeup air filter:
a) Control center inlet radiation monitor.
b) Reactor Building ventilation exhaust radiation monitor
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c E) Fuel pool ventilation exhaust radiation monitor.
d I) Low reactor water level.
e g) High drywell pressure. i
- 3. Verifying that on the chlorine mode actuation signal, the system automatically switches to the chlorine mode of operation, the isolation valves close within 4 seconds, and a minimum of 1200 cfm emergency recirculation is established.
- 4. Verifying that each of the emergency makeup inlet air heaters dissipate 12.0 + 2.0 kW when tested in accordance with ANSI N510-1980.
- f. After each complete or partial replacement of a train HEPA filter bank by verifying that the train HEPA filter bank satisfies the h
inplace penetration and bypass leakage testing acceptance criteria of less than 1.0% in accordance with ANSI H510-1980 while operating the system at a flow rate of 1800 cfm + 10% for the makeup train and 3000 cfm i 10% for the recirculation train.
- g. After each complete or partial replacement of a train charcoal adsorber bank by verifying that the train charcoal adsorber bank satisfies the inplace penetration and bypass leakage testing acceptance criteria of less than 1.0% in accordance with ANSI N510-1980 for a halogenated hydrocarbon refrigerant test gas while operating the system at a flow rate of 1800 cfm + 10% for the makeup train and 3000 cfm i 10% for the recirculation train.
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FERMI - UNIT 2 3/4 7-10