ML19318C126
| ML19318C126 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 06/06/1980 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| IEB-80-05, IEB-80-5, NUDOCS 8007010062 | |
| Download: ML19318C126 (9) | |
Text
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IHsconsin Electnc ma cower 231 W. MICHisAN, P.O. BOX 2046. M!LWAUKEE, WI 53201 June 6,1980 Mr. i. G. Keppler, Regional Director Office of Inspection and Enforcement, Region III U. S. NUCLEAR REGULATORY COMMISSION 799 Roosevelt Road Glen Ellyn, Illinois 60137
Dear Mr. Keppler:
DOCKET NOS. 50-266 AND 50-301 i
VACUUM PROTECTION OF LOW PRESSURE TANKS POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 Your letter of March 10, 1980, transmitted IE Bulletin 80-05, which is entitled " Vacuum Conditions Resulting in Damage to Chemical Volume Control System (CVCS) Holdup Tanks (sometimes called Clean Waste i
ReceiverTanks)".
This Bulletin requests that we review the design of all systems that contain low pressure or holdup tanks that can be valved to contain primary system water.
We have reviewed the following systems and tanks in regard to potential vacuum conditions that could result in tank damage with the potential for release of radioactive material or detrimental effects with regard to overall safety of plant operations.
A.
Waste Disposal System C.
Chemical Volume Control System D.
Safety Injection System E.
Sampling System The attachment to this letter contains our evaluation of the above systems in accordance with Bulletin 80-05. We have determined that suitable vacuum protection is provided for all potentially affected tanks except the CVCS holdup tanks. 0 GBT 39 1 9 007010 0 g g
Mr. J. G. Keppler June 6, 1980 A modification will be implemerted to prevent operation of the holdup tank recirculating pump unless there is positive pressure in the holdup tanks. We expect to have this modification completed prior to January 1,1981, dependent upon equipment availability.
The holdup tank recirculating pump is used only for the infre-quent transfer of large quantities of water. Should recirculating pump operation be performed, operations personnel are aware of the potential for Holdup Tank vacuum and have been instructed to, and as normal proce-dure to, operate the pump with the discharge throttled carefully monitoring the pressure in the holdup tank. Therefore, we consider continued reactor operation to be justified.
Please contact us if additional information is required.
Very truly yours, C/
,, - l/
, bO.
C. W. Fay, Dircttor Nuclear Power Department Attachment Copy to:
Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
20555 NRC Resident Inspector Point Beach Nuclear Plant
ATTACHMENT A.
Reactor' Coolant System 1.
Pressurizer Relief Tank (PRT) 100 psig @ 340'F a.
Design Conditions 3 psig @ Ambient b.
Normal Operating Conditions c.
Protective Features
- 1) High pressure alarm
- 2) High temperature alarm
- 3) High level alarm
- 4) Low level alarm
- 5) Nitrogen cover gas supply (approximately 27 cfm)
- 6) Periodic gas sampling for hydrogen
- 7) Tank is designed for 15 psig external pressure
- 8) Located inside containment
=
d, Vacuum Evaluation The-PRT is provided with a remote manually operated drain valve and drains by gravity to the Reactor Coolant Drain Tank (RCDT).
Failure of the low level alarm could result in complete drainage of liquid from the PRT.
This would be a continuation of the normal drain procedure.
The nitrogen cover gas supply rate is adequate.
There are no pumps which can be valved in to accelerate the drainage rate or cause a PRT vacuum.
Existing measures provide adequate vacuum protection.
Corrective action is not considered necessary.
B.
Waste Disposal System 1.
Reactor Coolant Drain Tank 60 psig @ 267'F a.
Design Conditions 0.5-2.0 psig @ 50-200*F b.
Normal Operating Conditions c.
Protective Features
- 1) High pressure alarm
- 2) High temperature alarm
_1_
n
- 3) High level alarm
'4) Low level alarm
- 5) Nitrogen cover gas supply (approximately 36 cfm) i
- 6) Periodic gas sampling for hydrogen
- 7) Tank is designed for 60 psig external pressure
-8) Located inside containment
- 9) Containmerat isolation trip of drain pump suction valves d.
Vacuum Evaluation Automatic RCDT' level control is provided which controls reactor coolant drain pump and pump inlet valve operation.
Failure of the level controller to shut off the drain pumps cou_d result in continued emptying of the RCDT.
The total available pump capacity is 200 gpm or 24.0 cfm.
The nitrogen cover gas supply rate is adequate to compensate for the maximum drainage rate.
Existing measures provide adequate vacuum protection.
Corrective action is not considered necessary.
2.
Wa:3te Holdup Tank (WHT) a.
Design Conditions O psig @ 180'F O psig @ 50-140*F b.
Normal Operating Conditions c.
Protective Features
- 1) High level alarm
- 2) Low level alarm
- 3. Two-inch free vent connection to building exhaust system d.
Vacuum Evaluation Liquid is removed from the WHT by local manual opera-tion of the waste condensate feed pump.
Pump capacity is 20 gpm or 2.4 cfm.. There are no other pumps which can be valved in to accelerate the drainage rate or cause a WHT vacuum.
The free breathing vent is adequate to compensate for the maximum drainage rate.
Existing measures provide adequate vacuum protection.
Corrective action is not considered necessary.
3.
Waste Condensate Tank (WCT) a.
Design Conditions O psig @ 180*F
^ psig @ 50-160*F b.
' Normal Operating Conditions c.
Protective Features
- 1) High level alarm
- 2) Low level alarm
- 3) Two-inch free vent connection to building exhaust system d.
Vacuum Evaluation Automatic WCT level control is provided which controls the waste condensate pump operation.
Pump capacity is 20 gpm or 2.4 cfm.
There are no other pumps which can be valved in to accelerate the drainage rate or cause a WCT vacuum.
The free breathing vent is adequate to compensate for the maximum drainage rate.
Existing measures provide adequate vacuum protection.
~
Corrective action is not considered necessary.
C.
Chemical Volume Control System 1.
Volume Control Tank 75 psig @ 250*F a.
Design Conditions 30 psig @ 127'F b.
Normal Operating Conditions c.
Protective Features
- 1) High pressure alarm
- 2) Low pressure alarm
- 3) High temperature alarm
- 4) High level alarm
- 5) Low level alarm
- 6) Borated water makeup (approximately 9.6 cfm)
- 7) Refueling water makeup (approximately 14.5 cfm)
- 8) Process gas return cover gas supply (approximately 1.5 cfm)
- 9) Hydrogen cover gas supply (approximately 1.5 cfm)
O-.
- 10) Periodic gas sampling for hydrogen concentration
- 11) Tank is designed for 15 psig external pressure d.
Vacuum Evaluation Liquid is removed from the VCT to the charging pumps.
The charging pumps are positive displacement pumps.
Two normally operating pumps have a capacity of 121 gpm or 14.5 cfm.
An approximately equal quantity of process liquids is returned ta the VCT.
Automatic level control is provided.
Borated water addition is initiated at low level setting.
The VCT discharge valve is closed upon continued decrease in level and charging pumps are fed from the refueling water storage tank (RWST).
Liquid can also be removed from the VCT to the holdup tanks or the RWST.
The maximum drainage rate would be through the refueling water circulating pumps at a rate of 100 gpm or 12.0 cfm.
Manual operation of both the VCT drain valves and the refueling water circulating pump is required to initiate this method of drainage.
Tank designs, VCT drain isolation and the multiple provisions for water and cover gas makeup provide adequate vacuum protection.
Corrective measures are not considered necessary.
2.
Holdup Tanks (HUT) a.
Design Conditions 15 psig @ 200*F 0.5-3.0 psig @ 130*F b.
Normal Operating Conditions c.
Protective Features
- 1) High pressure alarm
- 2) High level alarm
- 3) Low level alarm
- 4) Nitrogen cover gas supply (approximately 63 cfm)
- 5) Waste gas vent system cover gas (approximately 550 cu. ft. 5.0 psig minimum pressure)
- 6) Periodic gas sampling for hydrogen
,n
d.
Vacuum Evaluation Three holdup tanks are provided.
Liquid can be removed from a HUT by manual operation of a gas stripper feed pump or the recirculating pump.
Two 25 gpm gas _ stripper feed pumps are provided for a maximum drainage rate of 50 gpm or 6.0 cfm.
The recirculating pump capacity is 500 gpm or 60.0 cfm.
The maximum possible drainage rate is 550 gpm or 66.0 cfm.
No other pumps can be valved in to accelerate the drainage rate or cause HUT vacuum.
The vent system cover gas supply coupled with makeup nitrogen is normally adequate to provide suitable HUT vacuum protection.
Discharge from the recirculating pump is normally throttled to provide less than rated flow.
However, it is possible to manually isolate the supply of makeup nitrogen and to operate the recirculating pump at rated flow.
Suitable HUT vacuum protection would not be available for these operating conditions.
In order to assure that suitable HUT vacuum protection is provided, a pressure switch will be installed in the vapor space of cach HUT which will shut off the power to the recirculating pump when HUT pressure decreases to O psig.
3.
Monitor Tanks a.
Design Conditions O psig @ 125*F b.
Normal Operating Conditions O psig @ 100 F c.
Protective Features
- 1) High level alarm
- 2) Low level alarm
- 3) Diaflote membrane liquid cover
- 4) Four-inch diameter tank vent d.
Vacuum Evaluation Four monitor tanks are provided.
Liquid is removed from the monitor tanks by manual operation of the monitor tank pumps.
Redundant 60 gpm pumps are provided for a maximum possible drainage rate of 120 gpm or 14.4 cfm.
No other pumps can be valved in to accelerate drainage or cause monitor tank vacuum.
The Diaflote membrance and 4-inch atmospheric tank vent are adequate to compensate for the maximum drainage rate.
Corrective action is not considered necessary.
o
~4.
Concentrates Holding Tank (CHT)
.a.
Design Conditions O psig @ 250*F O psig 0 160'F b.
Normal Operating Conditions c.
Protective Features
- 1) High temperature alarm
- 2) Low temperature alarm
- 3).High level alarm
- 4) Low level alarm
- 5) Three-inch vent with loop seal d.
Vacuum Evaluation Liquid is-removed from the CHT by manual operation of.the CHT transfer pump.
Redundant 20 gpm pumps are provided for a maximum possi'ble draina.2 rate of 40 gpm or 4.8 cfm.
No other pumps can be valved in to accelerate drainage or cause CHT vacuum.
The loop seal depth is 12 inches.
The maximum possible tank vacuum is 0.433 psi.
The three-inch vent is adequate to. compensate for the maximum drainage rate.
Corrective action is not considered necessarv.
5.
Reactor Makeup Water Tank (RMWT)
-a.
-Design Conditions O psig @ 95*F b.
Normai Operating Conditions O psig @ 35-95'F c.
Protective Features
- 1) High level alarm
- 2) Low level alarm
- 3) Four immersion heaters
- 4) Diaflote membrane liquid cover
- 5) Siz-inch-tank vent d.
Vacuum Evaluation Two tanks-are provided.
The tanks are located in the containment facade which is weather protected but
. subject to outdoor ambient.
The four immersion heaters provide suitable freeze protection.
Liquid is removed from the RMWT by manual operation of the reactor W
- .o makeup water pump.
Redundant 270 gpm are provided for i
a maximum possible drainage rate of 540 gpm or 64.7 cfm.
There are no other pumps which can be valved in to accelerate drainage or cause RMWT vacuum.
The Diaflote membrane and six-inch tank vent are adequate to compensate for the maximum drainage rate.
Corrective action is not considered necessary.
D.
Safety In]ection System 1.
Refueling Water Storage Tank a.
Design Conditions O psig @ 95'F O psig @ 35-95'F b.
Normal Operating Conditions c.
Protective Features
- 1) Low level alarm (three stages)
- 2) Six immersion heaters
- 3) Diaflote membrane liquid cover
- 4) Six-inch tank vent d.
Vacuum Evaluation The RWST is located in the containment facade which is weather protection but subject to the outdoor ambient.
The six immersion heaters provide suitable freeze protection.
Liquid can be removed from the RWST by:
- 1) Redundant 700 gpm safety injection pumps
- 2) Redundant 1560 gpm residual heater removal pumps
- 3) Redundant 1320 gpm containment spray pumps
- 4) The 100 gpm refueling water circulating pump
- 5) Gravity 121 gpm supply to the charging pumps.
The maximum possible drainage rate could be 7381 gpm or 885 cfm.
There are no other pumps which can be valved in to accelerate the drainage rate or cause RWST vacuum.
The Diaflote membrane and six-inch tank vent are adequate to compensate for the maximum drainage rate.
Corrective action is not considered necessary.
E.
Sample System There are no low pressure or atmospheric tanks in this system.
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