ML19330B081
| ML19330B081 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 06/12/1980 |
| From: | Renberger D WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| ELE-GCS-80-175, IEB-80-05, IEB-80-5, NUDOCS 8007300299 | |
| Download: ML19330B081 (10) | |
Text
Y fl G.
~
NP Washington Public Power Supply System A JOINT OPERATING AGENCY S
5 r.o.e.....
3 000 c.o. w..
e ro,. w.,
a,c <.
- o. w..m.ro~. 3 3 2 o
s-sooo
, <g,,
June 12, 1980 M/
Y-
/ r[ 4 3 h ELE-GCS-80-175 i ' & s'n h.-j) / O Docket Nos. 50-460 t and 50-513 "/, ' p Mr. R. H. Engelken, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission 1990 N. California Boulevard Suite 202, Walnut Creek Plaza Walnut Creek, CA 94596
Subject:
WPPSS NUCLEAP, PROJECTS 1 AND 4-- RESPONSE TO IE BULLETIN 80-05
Dear Mr. Engelken:
The subject IE Bulletin, which addresses, " Vacuum Conditions Resulting in Damage to Chemical Volume Control System (CVCS) Tanks," has been reviewed by our technical staff for application to the WNP-1/4 nrojects. As a result of our review, it has been concluded that design changes to the existing WNP-1/4 low pressure process tanks are not recuired. A detailed discussion of the systers reviewed and the vacuum protection provided in those systems is included in the enclosure. Should you have any ouestions regarding our response, niease notify me. Very truly yours, Y D. L. RENBERGER Assistant Director Technology DLR:GCS :cnv Enclosure cc: Director, NRC Office of Insoection and Enforcement Mr. Bill Woods, NUS Corporation 8007300 N 'g 30'3I
c ~ s RESPONSE TO NRC IE BULLETIN NO. 80-05 1.
SUMMARY
The subject bulletin enumerates several instances of radioactive gaseous release resulting from damage to liquid process tanks due to vacuum con-ditions and calls for the actions to be taken by all PWR licensees and i permit holders to prevent recarrence of such instances. The design of all WNP-1 a~nd 4 systems (that contain low pressure or holdup tanks that can be valved in to. receive primary system water) was i reviewed with respect to the requirements of the subject IE Bulletin. It is found that the present design of these systems is adequate.to protect against vacuum conditions that could result in tank damage with the patential for rel, ease of radioactive material or detrimental effects with regard to overall safety of plant operations. 2. DETAILS OF REVIEW The systems reviewed with respect to the requirement of the subject IE Bulletin are listed in Table 1. Among all plant systems, the systems listed in Table 1 are identified to be those that contain low pressure , or holdup tanks that can be valved in to receive primary system water. Table 2 is a listing of such tanks and their design features provided for vacuum protection. The type of vacuum protect. ion provided for each tank is primarily determined by the nature of. its contents, which can be classi-fied into the following four groups: Group 1: 'The tanks containing primary water which when processed become the reactor coolant makeup water. The oxygen content of the reactor cool-ant makeup water must be 1.imited to 0.1 ppm. The tanks in the Chemical Addition and Baron Recovery System (BRS), and the R.C. Drain Tank of the Containment and Equipment Drains System (DFR) fall under this group. These tanks have a nitrogen cover gas at a pressure of 0.8.to 1.0 psig. provided by the Nitrogen Blanketing System (NBS). The rate of admission of the c,over_ gas into each tank is fast enough to keep up with the maximum rate of liquid removal from the tank, thus avoiding a vacuum condition. As a backup protection, each tank is provided with a vacuum breaker appropriately designed to preclude collapse of the tank under maximum expected vacuum cor. ti ti ons. ' Grou:: 2: The only _ tank in this group is the Makeup Tai.< (MUS-TK-1) which \\ n -,,3 w v. y,
W provide the reactor coolant makeup water. The gas cover of this tank is also used for oxygen scavenging of the reactor coolant by maintaining the ccrrect partial pre'ssure of hydrogen in the Makeup Tank so that specified equilibrium concentration of hydrogen remain dissolved in the reactor coolant. A nitrogen cover gas at a pressure of 15 to 35 psig. from the primary Gas System (PGS) prevents intrusion of oxygen into the tank. The presence of hydrogen inside the Makeup Tank precludes the use of a vacuum breaker because the air inflow into the tank under vacuum conditions may cause explosion inside the tank. However, the tank is provided with sufficient monitoring and protective instrumentation to prevent a vacuum condition that results in tank failure. The tank is provided with high and low pressure and level alarms. ~ In addition, the makeup pumps which take suction from the tank are provided with a low sucticn pressure trip at 5 psig. Based on the conservative assum: tion of the minimum initial pressure and volume of the cover gas and maximum final volume of the cover gas (the. tank and the suction piping of the makeup Pumps completely empty), the maximum expected vacuum for the tank is 7.59 p~si. which is well below its estimated maximum allowable vacuum of 9.95 psi. Thus the automatic pump trip feature will prevent the tank failure under vacuum. The makeup tank low pressure and low level alarms and level and pressure-indication give advance warning to the control room operator to take corrective actions such as making up the tank pressure and/or level, or tripping the makeup pumps, much before the automatic put p trip. The cperator has sufficient time to take these corrective actions af ter the above alarms are annunciated on the control room panel. Group 3: The tanks containing radioactive water with any significant quantities of radioactive gases or fumes are vented to the vent header of the Radioactive Vents & Drains System (RVD) and processed through a filter train. Because these tanks are interconnected on their gas space through their vent connections to the RVD vent header, the air will flow between-tanks for any internal transfer of liquid within this group, and therefore, will prevent severe vacuum conditions. For an external transfer of liquid from any of these tanks, the design of the RYD vent header connection to the filter train permits backflow of air through the header into the tanks, which again prevents any severe vacuum conditions. The vent lines and the RVD header are of adequate size to provide sufficient backflow of air so e
3 that the maximum expected vacuum is less than the maximum allowable vacuum for each tank under this group. Grouc 4: The tanks containing radioactive liquid with little or no radioactive gases or fumes are vented directly to the atmosphere inside the building. The air from the area is further treated by the area HVAC systems. The sizes of vent lines are adequate to provide sufficient backflow into the tanks to prevent failure of the tanks under vacuum. 3. ADDITIONAL DESIGN FEATU'lES a. No isolation valves are provided on the vacuum breaker or vent lines thus avoiding any possibility of their inadvertent closure which could mullify the vacuum protection. b. All tanks and,their vacuum protection devices are located indoors ~ where the temperature is controlled (minimum expected temperature is 55"i or above). Therefore, no freeze protec. tion is required. However, for the Concentrated Boric Acid Tanks (BRS-TK-3 & 4) and the Boric Acid Addition Tank (BRS-TK-10) heat tracing is provided on the "4- =nd the vacuum breaker / vent lines to prevent block-age o- . ines' due to crystallization of boric acid. c. Flame airestors are provided on the vent lines of R.C. Pump 011 Collection Tanks (DFR-TK-2 & 3) because oil fumes may be present in the vent gases. d. The pressure regulators (in the Nitrogen Blanketing System which controls the nitrogen pressure into the Group 1 tanks), the vacuum breakers, and the vent lines will be periodically tested / inspected to ensure their funct'ional operability in accordance with an acceptable surveillance program. 4. SAFETY ANALYSIS Safety analysis of small spills or leaks of radioactive material a. outside containment are found in Section 15.1.21 of the PSAR. b. Safety. analysis of inadvertent radioactive liquid releases are found in Section 15.1.33 of the PSAR. c. Safety analysis of' radioactive gaseous release are found in Section 15.1.34 of the PSAR. The environmental consequences of the above accidents are small and are of negligible consequences as shown in the abcVe sections of the PSAR.~
5 REVIEW ASSUMPTIOMS, Outficw of liquid from tanks is based on rated pump flow considering a. all normally valved in pumps operating, b. Equations for tank vacuum capability basec on ASME III and VIII codes (External pressure considerations) Flat top tanks - no credit taken for external stiffners. c. d. Vacuum Breakers - no credit taken for vacuum breaker relief capacity in excess of its specified capacity, Maximum flow resistance path assumed for calculating make up air e. pressure drops to vented tanks. 9 4 e a 8
~ TABLE 1 LISTIf!G OF 3YSTFMS REVIEWED 1. Chemical Addition and Baron Recovery (BRS) 2. Containment Spray (CSS) 3. Decontaminetion (DCN) 4. Containment Equipment and Floor Drains (DFR) 5. Spent Fuel Cooling and Purification (FPC) 6. Incore Monitoring (IMS) 7. Makeup and Purification (MUS) 8. Radioactive Liqui.d Waste (FLW) 9. Radioactive Solid Waste (RSW) 10. Radioactive Vents and Drains (RVD) G e r e i-m-,-r
bitUU I. A e _ san ** TABLE 2 VACUUf1 PROTECTI0tl FOR LOW PRESSURE PROCESS TAllKS V cuum Protection [e Tank flo. Description p b o
- 1) Fast pressure maken BRS-TK-1 R.C. Bleed Holdup Tank #1 3 psig 110,000 1
with blanketing fl 7
- 2) 2" Vacuum Breaker ~
- 1) Fast. pressure maken BRS-TK-2 R.C. Bleed lloldup Tank #2 3 psig 110,000 1
with blanketing fl2
- 2) 2" Vacuum Breaker
- 1) Fast pressure maket BRS-TK-3 Concentrated Boric Acid Storage Tank #3 Atmospheric 13,425 1
with blanketing !! 2
- 2) 2" Vacuum Breaker (with heat tracing)
II f,ft,( f)]t]nt ti 7 BRS-TK-4 Concentrated Boric Acid Storage Tank #4 Atmospheric 13,425 1
- 2) lh" Vacuum Breake'
- 1) F st pressure maket BRS-TK-5 Evaporator Distillate Test Tank #5 15 psig 7,975 1
vn th blanketing !! 2
- 2) 2" Vacuum Breaker
- 1) Fast pressure makei BR5-TK-6 Evaporator Distillate Test Tank #6 15 psig 7,975 1
vn th blanketing il 2 7.) 2" Vacuum Breaker
- 1) Fast pressure makei BRS-TK-7 R.C. Distillate Storage Tank #7 3 psig 100,000 1
with blanketing fl2
- 2) 2" Vacuum Breaker
- 1) Fast pressure makee BRS-TK-8 R.C. Distillate Storage Tank #8 3 psig 100,000 1
with blanketing fl2
- 2) 2" Vacuum Breaker BRS-TK-10 Boric Acid Addition Tank Atmospheric 12,040 4
- 1) 1" Vent to buildin-atmosphere (with la tracing)
- See text for classification of tank contents into 4 groups
bheet 4 ul 4 TABLE 2 VACUUM PROTECTI0tl FOR LOW PRESStlRE PROCESS TAflKS Pfe Vacuum Protection Tank flo. Description e 1 ) ou F CSS-TK-1 Borated Water Storage Tank Atmospheric 807,000 4 (1) Three 12" Vent to Building Atmosphi DCN-TK-1 Decontaminated Drain Collection Tank Atmospheric 5,000 4 (1) 3" -Vent to Buildi Atmospl.cre DFR-TK-1 R.C. Drain Tank 100 psig 12,230 1 (1) Fast Pressure mal with blanketing it (2) 2" Vacuum Breaker DFR-TK-2 R.C. Pump Oil Collection Tank #2 Atmospheric 500 4 (1) 3" vent to buildi a tmosphere (wi th flame arrester) DFR-TK-3 R.C. Pump Oil Collection Tank #3 Atmospheric 500 4 (1) 3" vent to buildi' atmosphere (with flame arrester) FPC-TK-1 Spent Fuel Pool Surge Tank 40 psig. 15,000 4 (1) 6" vent to the vicinity at area llVAC exhaust inta upstream of clean trains IMS-TK-1 Incore lionitoring System Tank Atmospheric 37,880. 4 (1) 12" vent to built a tmos phere MUS-TK-1 11akeup Tank 100 psig 9,148 2 (1) Suf ficient time i take corrective action (2) Low tank level as pressure alanas
- See Ie<t for classificatiorr of tank contents into 4 groups
Sheet. J of L TABLE 2 VACUUft PROTECTI0ft FOR LOW PRESSURE PROCESS TAtlKS Design Capacity Contents Vacuum protec tion Tank fio. Description Pressure (Gallons) by Group
- MllS-TK-1 tlakeup Tank 100 psig 9,148 2
(3) Lcw suction pressi trip for the raake plups RLW-TK-1 Liquid Waste Collection Tank A ' Atmospheric 2,400 3 (1) 4" vent to RVD ve. header llLW-TK-2 Liquid Waste Collection Tank B Atmospheric 12,000 3 (1) 4" vent to RVD ve header RLW-TK-3 Liquid Waste Collection Tank C Atmo< pheric 35,000 3 (1) 4" vent to RVD ve [ header RLW-TK-4 Liquid Waste Batch Feed Tahk A Atmospheric 4,400 3 (1) 4" vent to RVD ve header RLW-TK-5 Liquid Waste Batch feed Tank B A tmospheric 4,400 3 (1) 4" vent to RVD ve header RLW-TK-7 Liquid Was te Backflush Tank 65 psig 500 3 (1) 4" vent to RVD ve header RLW-TK-8 Liquid Waste Holdup Tank A A tmospheric 7,000 3 (1) 4" vent to RVD ve header RLW-TK-9 Liquid Waste Holdup Tank B Atmospheric 7,000 3 (1) 4" vent to RVD ve header RLU-TK-10 Liquid Haste Italdup Tank C Atmospheric 7,000 3 (1) 4" vent to RVD vc header RLW-TK-11 Liquid Waste lloldup Tank D A tmospheric 7,000 3 (1) 4" vent to RVD vt header
- See text for classification of tank contents into 4 qroups
c i i i n v v v v v v o s F D D D D D D p i t V V V V V V u c R R R R R R o e r t o o o o o o g o t t t t t t r P t t t t t t. 4 nr nr nr nr nr ir m ee ee ee ee ee ee o u vd
- v. d vd vd vd vd t
a a a a a n u a c " e " e " e " e " e " e i a 2h 2h 4h 3h 2h 2h s y V t ) ) ) ) ) ) 1 1 1 1 1 1 n ( ( ( ( ( ( e t u no c 4 u k n er t a ee n 3 3 3 3 3 3 t n f a o no i ta S ) c K { 0 0 0 0 0 0 i l t n 0 0 0 0 0 0 f tAT 5, 5, 2, 0, 0, 4 i s 3 3 4 5 5 1 s S i 1 1 1 3 a S l E c C O r R o P f l E c c c c c c t R i i i i i i x U e r r r r r r e S e e e e e e t S j h h h h h h E p p p p p p e 2 R s s s s s s e P e o o o o o o S E D m m m m m m t t t t t t L W p B O A A A A A A A L T ' R O F t f 0 I TC E T 1 2 OR k k P n n k a a n 1r T T a U k T U r r n C o o a n A t t T i V a a k a r r y n r a a a a D n p p c T o e e e r i S S D h e k t s w n p e e n u o a s s i l h T ir a a s F S c h h e n s P P R r t i e o a e D e e e z H r t t t i D s s s l a a a a l W H W r y a e r c d d d n d i i i i i n m l l l m u e o o o e a h S S S D L C io 2' 3 1 2 3 1 l K K K K K K k T T T T T T n a W W U D D D T S S S V V V R R R R R R .}}