ML20249C388
| ML20249C388 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 06/25/1998 |
| From: | Zinke G Maine Yankee |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GAZ-98-40, MN-98-49, TAC-MA0659, TAC-MA0660, TAC-MA659, TAC-MA660, NUDOCS 9806290175 | |
| Download: ML20249C388 (16) | |
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MaineYankee P.O. BOX 408 + WISCASSET. MAINE 04578 + (207) 882-6321 y
,- June 25,1998 W \
MN-98-49 GAZ-98-40 UNITED STATES NUCLEAR REGULATORY COMMISSION Attention: Document Control Desk Washington,DC 20555
References:
(a) License No. DPR-36 (Docket No. 50-309)
(b) Letter: M. J. Meisner to USNRC; Request for Exemption From the Financial Protection Requirement Limits of 10CFR50.54(w) and 10CFR140.11; MN-98-01, dated January 20,1998. See also, Letter: M.J. Meisner to USNRC; Defueled Emergency Plan and 10CFR50.54(q)- Exemption Request; MN-97-119, dated November 19,1997.
(c) Letter: USNRC to M. J. Meisner; Request for Additional Information For Exemption From Financial Protection Requirement Limits (TAC Nos.
MA0659 and MA0660; dated April 9,1998 (d) Letter: M. J. Meisner to USNRC; Response to NRC Request of Additional Information For Exemption From Financial Protection Requirement Limits; MN-98-27, April 13,1998 (e) Meeting Summary: M. K. Webb, USNRC; Summary of Meeting Held on June 9,1998, to Discuss Spent Fuel Heatup Analysis Performed by Maine Yankee Atomic Power Station; dated June 17,1998 (f) Letter: USNRC to M. J. Meisner; Second Request for Additional Information For Exemption From Financial Protection Requirement Limits (TAC Nos. MA0659 and MA0660; dated June 15,1998 (g) Letter: G. A. Zinke to USNRC; Response to NRC Request of Additional Infonnation on Maine Yankee's Spent Fuel Heatup Analysis; MN-98-45, June 18,1998
Subject:
Response to NRC Request for Additional Information on Maine Yankee's Spent Fuel Heatup Analysis;(TAC Nos. MA0659 and MA0660)
Gentlemen:
In Reference (b), Maine Yankee submitted requests for exemptions from the Emergency Plan and Financial Pmtection requirement limits of10CFR50.54 and 10CFR140.11. In Reference (d), Maine Yankee responded to an NRC request (Reference (c)) for additional information that the NRC believed was necessary to assist in reviewing the licensing requests. On June 9,1998, Maine Yankee met with the NRC to discuss Maine Yankee's spent fuel heat-up analysis. In these discussions, Maine Yankee provided answers to specific NRC questions. l/
Subsequent to that meeting Maine Yankee provided additional information in response to specific NRC questions (Reference (g)) . On June 23, the NRC verbally requested additional infonnation concerning Maine Yankee's spent fuel pool building temperature analysis (re: question 1, Reference (f)). g
~m oo L
In response to your question, an assessment of the Maine Yankee fuel building environment d temperatures following a beyond-design-basis postulated total loss of water in the spent fuel pocl {\ 0 is attached to this letter. Based on the results of the assessment, a maximum building temperature of approximately 210 degrees F would have been expected on January 15, 1998 during the postulated beyond-design-basis event.
l 9806290175 990625 PDR ADOCK 05000309 -
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. MaineYankee UNITED STATES NUCLEAR REGULATORY COMMISSION MN-98-49 Attention: Document Control Desk Page 2 We believe that this response should provide sufficient information to complete the NRC review of the beyond design basis spent fuel heatup analysis, and understand that approvals for both the emergency planning and financial protection exemptions should be forthcoming in early July,1998.
The designated point of contact for this information is Mr. Robert P. Jordan; Manager, Analysis, (207-882-5688). 'If you have any questions, please contact us.
Very truly yours,
, ($_ $
George A. Zinke, Dire or Nuclear Safety & Regulatory Affairs Attachments
- c: Mr. H. J. Miller Mr. M. K. Webb -
Mr. M. Masnik Mr. R. Bellamy Mr. P. J. Dostie Mr. U. Vanags i
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, . Maine Yankee Assessment TITLE: SIMPl.lElED ASSESSMENT OF FUEL BUILDING ENVIRONMFEI TEMPERATURES FOLLOWING TOTAL LOSS OF WATER IN THE SPENT FUEL POOL This assessment is prepared as supporting information to other detailed calculations addressing a beyond design basis event (References 1,2, and 3). As such, it is not intended as a safety related calculation or as input to a safety related calculation or application.
Purpose:
Inherent in the Maine Yankee zirconium heatup analysis (Reference 1) is the parameterization of the fuel building environmental air temperatures when exposed to the spent fuel without the ,
cooling effects of the pool water. This parameterization was necessary at the time the zirconium j heatup analysis was performed because a more complete treatment of the building environment had yet to be performed.
The building air temperatures are used as boundary conditions for the natural convective cooling l of the spent fuel following an instantaneous, non-mechanistic, loss of all spent fuel pool water. l As such, they were shown to be an important variable in Reference 1 for determining the spent fuel cladding temperature response. The zirconium heatup analysis parameterization of the building air temperatures ranged from 100F to 400F, in steps of 100F.
In order to appraise the validity of the assumed air temperatures, a simplified assessment of the fuel building environmental temperatures is performed in this calculation. 4 Fuel Building
Description:
The Maine Yankee fuel building is described in the DSAR, section 3.2.1 with the ventilation system described in section 3.3.5.1. These sections are attached to this calculation. Additional background information is contained in the Fuel Storage (3.3.1) section; however, it is not I attached.
Relevant information related to this calculation is as follows:
Building outside surface area 19200 square feet l Fuel Building surface Steel skin composite sandwiching insulating i panels Ventilation exhaust to outside 12000 cfm Page 1 of 8
P Euel Buildind Heat and Mass BalallCE
[
l Representation of the spent fuel building, as appropriate for these purposes, is a simplified balance between the energy input to the building from the spent fuel, the energy transferral to the outside through building losses and ventilation, and the absorption of energy by in flowing air.
Likewise, the mass flow into the building is conserved with the mass exiting the building.
Schematically, this representation is portrayed as:
Building Heat Losses (Qn,)
Building '
Building Ventilation . - Ventilation Gain
. . ' Exhaust (Q .,m ,,m.,,)
T Inside (o m..) -
^ ........
- Toutside (Fuel Building Decay Aeatinput from Spent Fuel (Qan)
Listino of Kev Assumptions:
Based on the type of simplified analysis contained within this calculation, a number of assumptions have been defined. The following are considered the more important assumptions:
- 1. The conservative assumptions identified in Reference 3, as applicable to defining this problem, apply.
- 2. The calculation is performed at steady state conditions and assumes no change in temperature of the spent fuel, building structures or equipment, or environment.
- 3. The effect of water or steam in condensing on the building walls has been neglected.
- 4. The mechanism for heat transfer through the building walls is convective limited.
Differences between the makeup of the building walls and/or doors is neglected.
- 5. All fuel building doors remain closed and the building sealed.
- 6. The building surface convection heat transfer coefficient is based on free convection to air. See Attachment A.
8
Heat and Ma'ss Balance Eauatjsnit The simplified equations goveming the flow of heat and mass into and out of the fuel building are as follows:
- 1. O ,+Oy =O +Om or, Q, = Q,,+ Om - Q, and, m,,= m y+ m i o ,
- 2. O, = 1.11 MW, or 3.79 x 108BTU /hr Based on a total pool inventory decay heat calculation for January 15,1998, Reference (2).
- 3. Om = h A (T ,,, - Tu .)
Based on the assumption that the heat transfer is convective limited on the outside of the fuel building. This assumption is additionally discussed in Attachment A to this calculation.
h = Convective heat transfer coefficient = 1.25 BTU /(hr ft2 p)
A = Building surface area exposed to outside air temperatures
Approximately 19,200 square feet T,n ,o, = unknown Tu ,,o,
Assumed to be 87F (summer conditions)
- 4. O, = m., (C, ) a. (T,n o. - T )
Based on the removal of energy from the fuei building at design flows of the ventilation system.
m, = Ventilation system mass now n:te = (12000 cfm) p,n,,,; or, (720,000 cfh)p,n,,,..
Note: p,n.,o, is the 6snsity of air ituide the fuel building and is a temperature dependant function.
(C,),n,4,= Air specific heat inside the fuel building Note: C,is a temperature dependant function
- 5. Oy = my(C,) o. (Tu,,o, - T,n ) + mo i,, {(C,).1,,,(Tu ,,,,-212) - hy
=ts,4.
Based on the addition of cooler and moister outside air into the fuel building and the heatup of such air and moisture.
Page 3 of 8
t
- (C,) i.o,= Air specific heat outside the fuel building = 0.240 Btu /lb,F (C,),,,,, = Water specific heat outside fuel building = 0.998 Btu /lb, F m, = Air mass flow = m,,- m.,io, h,, = Heat of vaporization for the water (~976 Btullbm )
m 1.,
= Water mass flow as based on the ASHRE 1% limits for Portland, Maine (summer): At 87F (dry) and 72F (wet) air, there are 94 grains of ' water per pound of dry air. The mass of dry air is the same as entering the fuel building (m ,).
= (94 grains /7000 grains per Ibm)(m.,)
= 0.0134 (m ,)
Since the solution of the above equations is dependant on the building temperature, an iterative method is used. A summary of the results of this method are provided below:
Properties Table:
T,,,,o, (F) p,,,, (C,),n,o, 3
(Ibm /ft )* (Btu /lb, F)*
200 0.01605 0.241 225 0.01421 0.2415 250 0.01237 0.242 Assumed at a pressure of 1 atmosphere.
Calculation Table:
T, Om O,, Q,, Oon (Btu /hr) Oon (Btu /hr)
(F) (Btu /hr) (Blu/hr) (Btu /hr) (calculated) (actual) 200 2.712E06 0.314E06 -0.477E06 3.503E06 3.79 E06 225 3.312E06 0.341E06 -0.483E06 4.136E06 3.79 E06 Based on the relative increase in the calculated value of Oon as compared to the actual decay heat, Oon, additional calculations are not deemed necessary.
As is observed from these calculations, the relative importance of the heat transfer through the building walls (Om) is significant. Since the wall surface area is a constant, the amount of heat transferred is linearly dependant on the influence of the heat transfer coefficient. With a decrease of 50% of the assumed value of this parameter, the corresponding building intemal air temperature rises approximately an additional 100F to between 300F and 325F. See Attachment A for a discussion of the building wall heat transfer coefficient and the suitability of the assumption that the heat transfer through the wall is convective limited.
Page 4 of 8
Conclusions:
Based on the results of the foregoing calculation,, the simplified heat and mass balances for the fuel building indicate a conservatively determined ambient air temperature of approximately 210 F. This value is representative of a decay heat loading comparable to January 15,1998.
Temperatures above this value would not be expected to occur give7 the conservative assumptions of the analysis.
References:
- 1. Propnetary Report,"Scientech Inc. Evaluation of Spent Fuel Pool Cooling Scenarios for Maine
. Yankee", SCIE-COM-5654-97, dated January,1998.
- 2. Proprietary Report,
- Evaluation of Maine Yankee Spent Fuel Building Response to a Loss-of-Decay Heat Removal Accident", SCIE-COM-5654-98, dated January,1998.
- 3. Letter, Ma!ne Yankee to NRC,
- Response to NRC Request for Additional Information on Maine Yankee's Spent Fuel Heatup arialysis", MN-98-045, dated June 18,1998.
) Attachments:
A. Discussion of Building Wall Heat Transfer B. Defueled Safety Analysis Report sections 3.2.1 (Fuel Building) and 3.3.5.1 (Fuel Building Ventilation System)
4 ATTACHMENT A
. BMjLDING WALL HEAT TRANSFER As 10 seen in the foregoing calcu!ation, the effectiveness of the fuel building wall heat transfer controls the building internal air temperature. Hence, additional discussion is warranted regarding the selection of the heat transfer coefficient and the effect of the wall composition in validating the assumption of a convective limiting problem.
HeatTransfer Coefficient The heat transfer coefficient selected was based on ihat proposed by McAdams' for a free convection problem resulting from heated vertical and/or horizontal surfaces to air, assuming a turbulent flow condition.
With respect to validating the turbulent flow assumption, the transition between laminar and turbulent flow is defined as satisfying the following relationship: Gr, Pr, > 108 . With nominal parameters related to the fuel building heatup problem, it is easily determined that the flow of air along a wall in excess of approximately 3 feet results in a turbulent flow. The conditions for a stable laminar flow, either inside or outside the fuel building cannot not be satisfied. Hence, the use of a turbulent flow based correlation is reasonable.
The McAdams simplified correlations for free convection from vertical and horizontal surfaces to an air medium at atmosp.cric pressure are expressed as:
Vertical planes: h = 0.19 (AT)"' Btu /(br ft2 p)
Horizontal planes h = 0.22 (AT)"8 Btu /(br ft2 p)
Where AT is defined as T - T.,. (in this case, T. = 87F)
The following is a tabular listing of the range of heat transfer coefficients applicable to the fuel building heatup problem:
T, = 100F T = 200F T, = 300F T, = 400F Vertical surface 0.446 0.918 1.134 1.290 Horizontal surface 0.517 1.063 1.314 1.494 Given the combination of vertical and horizontal building surfaces, a composite heat transfer coefficient of 1.25 is appropriate.
It is worth noting that this value, although appropriate for a free convection assumption, is extremely conservative for a forced convection situation. Given that the fuel building is located outside in an uncontrolled environment, the use of a much larger (typically in excess of 10-100 times) forced convection heat transfer coefficient would be justified.
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8 McAdams, W.H.; Heat Transmission. 3rd edition, McGraw-Hill Book Company,1954.
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Effect of Bulldina Wall comoositten The fuel building walls consist of a sheet metal covered " sandwich of rigid insulation. The fuel building ceiling has the added component of a layer of roofing cement. In a simplified schematic, this arrangement may be viewed as follows:
Roofing layer Outside sheet metal layer Rigid insulation
\ inside sheet metal layer The composition of the fuel building walls, on a simplified basis, may be represented by a lumped parameter system, See Holman 2for a discussion of this approach. Such an analysis of the transient heat conduction, as coupled with a convective boundary condition on both the inside and outside surfaces, is dependant upon the principal temperature gradient occurring through the fluid layer at the surface.
Inherent in this type of simplified analysis is the uniform temperature distribution through the solid body and the assumption that the surface convection resistance is large compared with the internal conduction resistance. Holman identifies the following relationship as defining the applicability of such an analysis:
- [h (V/A)/k] < 0.1 Where, h is the heat transfer coefficient, V is the volume of material, A is the surface area, and k is the thermal conductivity of the solid.
In the case of the fuel building, the following apply:
h = 1.25 Btu /hr ft2 p V = 3200 cubic feet A = 19200 square feet k = 6.3 Btu /hr ft F (as based on a composite wall)
[(1.25)(3200/19200)/6.3] = 0.033, which is less than 0.1.
Therefore, the assumption of a convective limiting boundary condition controlling the building interior temperature is found to be appropriate.
2 J.P.Holman, tient. Transfer, third edition, McGraw Hill Book Company,1972.
Page 7 of 8
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ATTACHMENT B MAINE YANKEE I
DEFUELED SAFETY ANALYSIS REPORT Sections 3.2.1 (Fuel Building) 3.3.5.1 (Fuel Building Ventilation System) 4 Page 8 of 8
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4 MYAPC I 3.2
- Structures 3.2l1 Fuel Building h
- 1 3.2.1.1 General The principal function of the fuel building is to provide a location for the safe storage of new and spent fuel assemblies. The building houses a new-fuel unloading area, a new-fuel storage room, a spent fuel pool and the necessary cranes required for the handling of the fuel assemblies. The spent fuel pool cooling system heat exchanger, the fuel pool cooling pumps and the fuel pool purification pump are located in the area adjacent to the solid waste disposal equipment. The equipment decontamination area and the spent fuel pool support systems are also located in the fuel building. The fuel building arrangement is shown on Figures 3.2-1 and 3.2-2.
3.2.1.2 Fuel Unloading Area
.- - New fuel was shipped to the site in two-element shipping casks. A five-ton overhead crane in the fuel building'was used to unload the shipping casks. The spent fuel pool purification system filters and demineralized are located in shielded cubicles below the fuel unloading area. Shield slabs are removed from the fuel unloading floor to replace expended filter cartridge elements.
l 3.2.1.3 New Fuel Storage Area The new-fuel storage rcom is designed for storage of 160 fuel assemblies. The fuel room is located over the solid waste disposal area and the spent fuel pool cooling pumps and heat exchanger. The fuel rack consists of guide sleeves symmetrically located on the floor at Elevation 31 ft.1-1/2 in, and through the ceiling of the new-fuel room at Elevation 44 ft. 6 in. The fuel room
. floor has a drain opening located over the spent fuel pool cooling equipment cubicle. The floor
- opening prevents flooding of the new-fuel storage area. The spent fuel pool new-fuel elevator winch is also located in the new-fuel storage room.
3.2.1.4 Spent Fuel Pool Cooling of the spent fuel assemblies during the radioactive decay period is accomplished in a stainless saellined reinforced concrete pool filled with borated water. Space is provided in the pool to place ice spent fuel shipping cask. The poolis serviced by means of the yard crane, as well r
' DSAR 3-28 Rev.14 l
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t MYAPC as a moveable platform with hoist. A new-fuel area adjoins the spent fuel pool. The pool is designed to safely resist the hypothetical earthquake or tomado, as well as the applied loads of the wat'er and fuel.
The pool has a reinforced concrete floor founded on rock and sidewalls 6 feet thick which extend l from 12 feet 6 inches below ground grade to 26 feet above ground grade. The concrete is
- reinforced with #11 bars at 12 inch center to center spacing with a yield strength of 40,000 psi. The concrete has a 28 day minimum compressive strength of 3,000 psi. The reinforced spent fuel pool was originally designed in accordance with ACl-318-63 to resist the appropriate dead, live, hydrostatic and maximum hypothetical seismic loadings. The structure was reanalyzed, in support of EDCR 92-111, to demonstrate the acceptability of installing the new high density spent fuel storage racks.
As part of the preliminary decommissioning activities, the structural evaluations have been performed which demonstrate the adequacy of the SFP concrete and liner to withstand the effects of dead, live and hydrostatic forces in conjunction with an elevated pool water temperature of 212*F. Complete details of this evaluation are contained in References 3.2-1 and 3.2-2.
The pool is ompletely lined with plates of stainless steel which have test channels behind each weld. The test channels are piped to the spent resin pit sump through four-1 inch tell tale pipes, each with a flow limiter at the end of the pipe, in the event of a malfunction of a liner weld, the ]
leakage through each telltale is limited to less than 2.5 gpm. ]
The liner is designed as a ASME Section 111, Division 2, Paragraph CC-3720, Liner, Table CC-3720-1, Service Category, Membrane. The plate materialis ASTM A240, Type 304 stainless steel.
Liner Anchors are designed to ASME Section lit, Division 2, Paragraph CC-3730 and are constructed of ASTM A-36 steel. The weld rods used to weld the vertical stifwner flanges to the liner wall liner were ASTM E309 (carbon to stainless steel) with a minimum tensile strength of 81,000 psi.
The fuel transfer tube was originally designed as safety class 2; however, since the containment integrity design basis is not applicable in the defueled condition, it has been reclassified as safety class 3. It consists of a 36-inch OD,3/8 inch thick, ASTM A312 TP304, stainless steel pipe installed inside a 40-inch OD stainless steel sleeve as shown in detail on Figure 3.2-13. The inner pipe acts as the transfer tube and connects the containment refueling canal with the spent fuel pool and is welded to the fuel pool stainless steel liner. The outer pipe is fitted with bellows expansion joints, backed up by a packed slip joint to compensate for any differential movement.
l DSAR 3-29 Rev.15 l
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MYAPC Structural sfeel supports a superstructure of protected metal siding which encloses the pool. The steel framing above the pool is designed for earthquake and tornado to prevent it from falling into l
the pool and damaging fuel assemblies. The masonry wall at the south end of the fuel building is not designed for certain wind or earthquake loadings, and, therefore, an evaluation of the consequences of a wall collapse was performed. The analysis demonstrated adequate spent fuel pool cooling capability and structural rack integrity.
3.2.1.5 Fuel Storage Racks I
The new and spent fuel pool structures including fuel racks are designed to withstand the l anticipated earthquake loadings as Class I structures in accordance with the guidance of Regulatory Guide 1.29. Analyses show that the racks will perform their intended function under j both seismic and load drop loadings in accordance with Regulatory Guide 1.124 and NUREG-0800. I The design ensures that during the event, rack-to-rack and rack-to-wallinteraction is appropriately considered. Structural material used in the rack design is ASME Section 11, SA 240, Type 304 stainless steel. The design considered thermalloads induced by an operating temperature of 154*F. Subsequently an evaluation was performed which documented the acceptability of the racks at a temperature of 212*F. The ANSYS version 4.4A program was used for all computer aided mechanical analysis.
The design considered impact loads from a fuel element dropped from 18 inches above a module, a fuel element hangup during removal, and the load induced if an assembly hit the top of a rack I while moving at the maximum horizontal velocity of the crane. The dropping of objects over the ;
storage array was conservatively analyzed by assuming that the dropped object is twice the weight l 4 of a standard assembly. Subcriticality and a coolable geometry are maintained and damage to the
< stored fuelis minimized.
The racks consist of individual storage cells joined into a rack module. The racks are a single tier, rectilinear array of free standing modules, not anchored to the pool walls, floor or adjoining racks.
Each rack module is provided with adjustable support feet. Each fuel rack is a folded metal plate assembly of 14 gage metal, approximately 180 inches high,117 inches wide and 128 inches deep.
The folded metal plate asserably is welded to a baseplate, wh'ch is supported by adjustable supported feet. Region I contains 5 racks, spaced on a minimum cf 10.5 inch centers. Region il contains 21 racks spaced on a minimum of 9 inch centers. Spent fuel storage racks may be moved only in accordance with written procedures which ensures that no rack modules are moved over fuel assemblies.
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DSAR 3-30 l
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MYAPC 3.3.5 l :, Ventilation Systems Ventilation systems are designed to provide a suitable environment for equipment and personnel.
These systems provide heating and air conditioning. The ventilation systems utilize fans, filters,
. dampers, heating elements, cooling elements, and duct work to accomplish the desired effects, in
' the radiologically controlled areas, the fuel building and the primary auxiliary. building, outdoor air
. is supplied to these structures. Air is exhausted in greater quantities than it is supplied to maintain the building at a negative pressure and ensure that the general flow of air is into the structure. The exhausted air is discharged past radiation monitors in the primary vent stack or Fuel Building ]
exhaust duct. ]
Relocated Technical Specification Definition of Ventilation Exhaust Treatment Svstem The Ventilation Exhaust Treatment System includes all systems designed and installed to reduce radioactive material in particulate form in effluents by passing ventilation through HEPA filters for the purpose of removing particulate from the exhaust stream prior to release to the environment.
Such systems are not considered to have any effect on noble gas effluents. Engineered Safety Feature (ESF) atmospheric cleanup systems are not considered to be Ventilation Exhaust Treatment Systems components.
3.3.5.1 Fuel Building Ventilation System ,
3.3.5.1.1 Design Basis The fuel building ventilation system is designed to: maintain the operability of the fuel building ]
equipment during normal operating conditions, ensure that air flow is from outside into the building ]
to prevent unmonitored release of radiation, and ensure that exhaust air is continuously monitored.'
3.3.5.1.2 System Description
' Engineering has replaced the existing fuel building ventilation system with one designed to support ]
the needs of the spent fuel pool island in accordance with Design Change Package (DCP)97-042. ]
. Variable speed exhaust fan HV-SFP1 draws from 2000 cfm to 12,000 cfm of cooling air through a ]
louver and filter assembly in the northwest wall, and discharges the air through a duct mounted on ]
the exterior of the fuel building east wall. Before it is discharged to the outside, the exhaust air ]
passes through HEPA filters to remove any particulate materials. Because the exhaust system is ]
, once through, the fuel building is always maintained at a slight negative pressure. The heating and ]
. Rev.16
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MYAPC veritilation* equipment in the fuel building is designed to minimize moisture condensation on the walls ]
and the roof and to limit the space temperature to a maximum 95'F and a minimum of 60*F. A ]
radiation monitoring system is installed in the fuel building exhaust duct which continuously monitors ]
,, the discharge air to identify any potential releases. Fan FN-SFP1 supplies unconditioned building ]
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air to the heat exchanger cubicle to aid in cooling the components located there. ]
No ventilation systems are credited to prevent doses to control room personnel or the public for the credible spent fuel handling and storage incidents. Analyses indicate that following the design basis Fuel Handling incident which assumes an instantaneous puff release, isolation of the control room at t=6 minutes following the event and continuous recirculation over a 30 day period could potentially cause significant doses to control room personnel in the 3 Rem (Whole Body) range. This concem is abated to a 3 mrem (whole body) dose if the control room ventilation system is left in the existing mode of operation. "No action"in the event of this incident would result in a maximum 2-hour dose of approximately 3.3 mrem assuming an air intake rate between 120 and 900 cfm. Additionally, strict radiological controls are effected to minimize exposures to personnel ALARA.
3.3.5.1.3 'nsoection and Testina ]
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3.3.5.1.3.1 Fuel Building Ventilation System ]
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inside the fuel building is the fuel storage pool. The stored fuel will remain in the building until it is ]
transferred to dry-casks of off-site. The fuel building wil! remain independent of other systems, ]
structures, or components undergoing the decommissioning process, in this regard, the fuel ]
building ventilation system will remain operational. The fuel building ventilation system has ]
Administrative Controls established to ensure the following inspection and Testing requirements are ]
satisfied: ]
]
. Requirements for an operable ventilation system ]
. Requirements for demonstrating operability ]
. Requirements for testing and test frequency ]
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3.3.5.1.3.2 Control Room and Auxiliary Ventilation Systems ]
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The remaining ventilation systems consist of the Contrc' m /er.C ' on and Auxiliary Ventilation ]
Systems. These systems are in buildings where de" i activities will occur. Maine ]
Yankee has committed to the intent of NUREG/CR 01. The: 4 .a .aiation systems will be subject ]
Rev.16 DSAR Y?
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MYAPC to th'e testing and operability requirements of DSAR, Chapter 7. DECOMMISSIONING. ]
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3.3.'5.1.4 Design Evaluation ]
Since the consequences of the Fuel Handling Accident are significantly below 10CFR100.11 limits ]
without takir.g credit for the building ventilation, the fuel building ventilation system is not designated ]
to mitigate the consequences of a Fuel Handling Accident. There, the fuel building ventilation ]
system is not safety related.
3.3.5.2- Control Room Ventilation 1
3.3.5.2.1 Design Basis The control room ventilation system is designed to ensure habitability for personnel and proper cooling for equipment under normal and accident conditions.
3.3.5.2.2 System Description The control room air conditioning and ventilation system consists of air conditioning unit AC-18, ]
exhaust fan FN-15, path way to provide fresh air make-up and associated ductwork. The AC-1A ]
air conditioning unit is no longer available to provide conditioned air, however, the fan which is ] l I
Integral to AC-1 A may be aligned to supply fresh air to the control room if the AC-1B unit fails. No ]
credit for control room isolation is taken in the safety analyses and the doses to operators are still )
! well below General Design Criterion (GDC) 19 limits. Therefore, the control room ventilation system ]
no longer has an isolated operating mode. Not having an isolated operating mode eliminates the ] )
need for recirculation filters, filter booster fans FN-11 A and FN-11B, the breathing air inlet filters and ] l the breathing air fans FN-7A and 78. Therefore, these components have been abandoned and are ] l no longer part of the control room ventilation system. ]
The temperature in the control room may vary from 65'F to 85'F. Indicating and control instruments will continue to function within design accuracy in ambient temperatures up to 110'F. The control i room ventilation system is designed to preclude a total loss of cooling capability. The system consists of a 100% capacity air conditioning unit. If the air conditioner fails, then with control room ] l doors opened, the system will be operating on straight ventilation to maintain Control Room ]
temperature less than 110*F. ]
Rev.16 i
DSAR 3-108 '
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