ML19274D308
| ML19274D308 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 01/17/1979 |
| From: | Hoffman D COMMONWEALTH EDISON CO. |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7901230144 | |
| Download: ML19274D308 (17) | |
Text
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D General Offices: 212 West Michigan Avenue. Jackson. Michigan 49201
- Area Code 517788-0550 January 17, 1979 Director, Nuclear Reactor Regulation Att Mr Dennis L Ziemann,' Chief Operating Reactors Branch No 2 US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-155 - LICENSE DPR-6 BIG ROCK POINT PLANT - FIRE PROTECTION MODIFICATIONS By letter dated December 8, 1978, Consumers Power Company committed to providing an implementation schedule for proposed fire protection modifiestions at the Big Rock Point Plant by mid-January 1979.
The following provides a best estimate schedule and updated responses to the December 8, 1978 letter.
The individual schedule dates provided below are subject to change with the exception of the commitment to complete all modifications discussed in P26 below.
Item 32 At the present time, approved fire doors have been installed in all but three door openings through the fire barriers.
These three openings are equipped with good substantial doors that are equivalent to approved fire doors. These doors, due to their substantial construction and their equivalency to fire doors, will remain in place without modification.
The doors that will not be modified are located between (1) Room 124 (track alley) and Room 125 (condensate pump room), (2) Room 104 (shop) and Room 104A, (3) Room 105 (air compressor and electric room) and Room 101 (lobby).
The combination of two fire doors between Room 326 (turbine floor) and Room 308 (viewing area) have been accepted by the NRC inspection team of October 10-13, 19i8 as being equivalent to the three-hour barrier. These doors will not be upgraded and will remain in place without modification.
Other miscellaneous penetrations will be sealed by the end of the 1980 refueling outage.
790123ot@
2 Item 33 This item will be addressed by a separate letter before February 1979.
Item 34 Self-contained battery powered lighting units will be installed by November 1979.
Item 35 Final design not yet complete.
Item 36 Our December 8, 1978 letter completed this item.
Item 37 Our December 8, 1978 letter completed this item.
Item 38 Results of an analysis of the potential for dam' age to safe shutdown equipment by a hydrogen explosion in the off gas system is provided as Attachment I.
Item 39 Fire doors equipped with fusible link closure devices will be completed by April 1979.
Item 40 Our December 8, 1978 letter completed this item.
Item 41 Our December 8, 1978 letter completed this item.
Item 42 Our December 8, 1978 letter completed this item.
P5 Independent safe shutdown capability will be provided as identified in our December 8, 1978 letter. The schedule for this item is dependent on final design and interfaces with the SEP prcgram.
3 E5 Preliminary results of an evaluation for protective measure to preclude the potential for a fire causing inadvertent actuation of the RDS indicate that insulation of control / power cables with Kaowool will provide adequate protection. The modification will be complete by January 1960.
El This modification will be complete by March 1980.
Special insulation will not be required as identifed - Attachment II.
[8 This modification will be completed by September 1979.
E9 Cur letter of December 8, 1978 completed this item.
P10
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A portable water " Loaded Stream" extinguisher has been provided at the bailer house.
Pil This item will be completed during the 1980 refueling outage currently scheduled for February and March 1980.
P12 Same as Item P11.
P13 Installation of all fire detection and alarm systems will be completed during the 1980 refueling outage, currently scheduled for February and March 1980.
P14 This item is complete.
P15 Our letter of December 8, 1978 completed this item.
P16 Equipment will be ordered and placed in service by August 1, 1979.
4 P17 Equipment will be ordered and placed in service by August 1, 1979.
P18 One 5000 cfm smoke ejector will be ordered and placed in service by August 1, 1979.
P19 Equipment will be ordered and installed by December 31, 1979.
P20 Equipment will be ordered and placed in service by August 1,1979.
P21 Procedures will be written by February 15, 1979 to document the required test.
Post winter testing will be completed by June 1, 1979.
P22 Was completed December 8, 1978.
P23 Was completed December 15, 1978.
P24 One fire depot has been established and a second assigned. The second depot will not be functional until the security modification is completed. Expected date for the second depot is June 1, 1979.
P25 This item is part of Consumers Power planned fuel pool rack modifications and will be submitted by June 1979.
5 P26 This item was addressed completely in our December 8,1978 letter with the exception of an overall commitment for completion schedule for all fire protection related modifications.
Consumers Power intends to complete all fire protection modifications before the end of 1980 with the possit.
exception of the independent safe shutdown capability which is still being evaluated.
David P Hoffman (Signed)
David P Hoffman Assistant Nuclear Licensing Administrator CC JGKeppler, USNRC
e ATTACIDENT I e
9
BIG ROCK POINT PLANT ANALYSIS OF HYPOTHESIZED HYDROGEN EXPLOSIP" EFFECTS FROM THE OFF-GAS SYSTEM AS RELATED TO SAFE SHUTDOWN 3
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The following analysis is provided as s response to Request #38 fron Enclosure 1 of the NRC letter to D A Bixel dated 12/20/78.
Request #38 Provide the results of an analysis of the potencial for damage to safe shutdown equipment by a hydrogen explosion in the Off-Cas System.
Conclusion Based on our letter of April 11, 1978 and the system design as summarized in the FHSR and the analysis below, there appears to be no off-gas explosion potential that could completely cripple safe shutdown capability at Big Rock Point.
Discussion:
1.
CPC0 submittal to NRC of April 11, 1978 in response to I E Bulletin 78-03 indicates the very low probability of external accumulatien of hydrogen from postulated Off-Gas System leakage with ventilation equipment in service (attachment).
2.
FHSR Section 9.1.7 indicates that the Off-Gas System is designed to with-stand the calculated pressures for an internal explosion (attachment).
3.
Notwithstanding the low probability of hydrogen accumulation or explosion potential as outlined in Response 1 above; a review of interior areas where off-gas leakage could accumulate with ventilation systems disabled has been conducted with reference to the Success Tree for Safe Shutdoun, VII-9 and System List VII-10 from the 3/29/77 submittal to the NRC (attachment).
a.
Stack base area and radwaste area - only off-gas and stack gas monitor-ing components are located here and loss of both systems would not pre-clude safe shutdown via the Poison System / Clean-up Isolation / Emergency Condenser path or the Scram / Containment Isolation / Emergency Condenser /
Shutdown Cooling System path.
b.
Lower turbine hall and condensate pump room - elements of the Condensate System, Demineralized Water System and Feedwater System are located here but complete loss of these systems would t.ot prevent safe shutdown via the Emergency Condenser / Poison System / Clean-Up System Isolation / Shutdown Cooling System path or the Scram / Containment Isolation / Emergency Conden-ser/ Shutdown Cooling System path.
Turbine pipe tunnel - elements of the Fire System, Demineralized Water c.
System, Service Water System, Instrument Air, Condensate System, Air Ejector System, Containment Isolation System and Feedwater System are located here.
- 1) The safe shutdown path utilizing the Poison System / Clean-Up System Isolation / Emergency Condenser System would not be affected.
- 2) The p'pe tunnel has blocout panel protection for high energy pipe rupture that would limit pressure rise to preclude pipe tunnel struc-ture damage per the submittal to the NRC of June 29, 1973.
- 3) Assuming that missiles generated by an explosion disabled the Fire System, such failure could be isolated by manual valving and the
Off-Cas Explosion Analysis (Contd) 2.
alternate supply path through MO-7072 could. replenish the emergency condenser.
- 4) Assuming that missiles generated by an explosion disabIed the service water supply to containment, the Fire System tie to the Service Water System in containment could be utilized for the Shutdown Cooling System.
- 5) If the service water discharge from containment were ruptured by ex-plosion effects, the Shutdown Cooling System would not be considered operable; however, the Poison System / Clean-Up Isolation / Emergency Con-denser System path would still be intact as well as the Scram /Contain-ment Isolation / Emergency Condenser path for safe shutdown.
- 6) If any of the external containment isolation valves or associated pip-ing were disabled in the open condition by explosion effects, the re-dundant isolation valves inside containment could still provide con-tainment integrity if needed for safe shutdown.
- 7) If the Demineralized Water System were disabled, makeup to the emergency condenser could still be provided by the normal Fire System or, if it were disabled also, the fire water path through MO-7072 could be used.
- 8) Loss of instrument air would not prevent use of the Emergency Condenser System, the Poison System, Scram System, Containment Isolation or Shut-down Cooling System. The Clean-Up System could also be isolated by manual valving. Thus, at least two safe shutdown paths could be used, namely - Poison / Clean-Up Isolation / Emergency Condenser / Shutdown Cool-ing System path or the Scram / Containment Isolation / Emergency Condenser /
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Shutdown Cooling System path.
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MANUAL POISON
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ISOLATE CU SYSTEM
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ISOLATION NON-FEECWATER FEEDWATER INITIATE i
ISOLATION W/ TSV W/ SJAE EHERGENCY C0!; DENSER g
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AUTO MANUAL SJAE CLOSE 110 7053 r
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& MO 7065 CVS. WCS, CHECK SGM v
CV 4020 EMERGENCY OPErl AND C0tl0ENSER INJECT CDS POISON
-t300 psia m
E AUX SYSTEMS: DWS OR FPS 3h0 psia LOSE SJAE RCW SW5 CR FPS 1
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<300 psia RCW RCW SWS Ok SW5 OR FPS FPS 1
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NOTE: This drawing, submitted as part FIGURE 3 of the Fire Analysis with CPC COLD SHUTDOWN letter to NRC of 3/29/77,.has Big Rock Point been modified to show deletion SUCCESS Tree for Safe Shutdown of core spray system per CPCo letter to NRC of 7/14/78.
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.~.Y FIrVRE 3 (Cont.)
BIG ROCK POINT SUCCESS TREE FOR SAFE SHUTD0!#l SYSTBi CODE E.C.S.
Emergency Condenser System i
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Demineralizer Water System
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Fire Protection System 76 R.C.P.
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^3 Reactor Cooling Water R.C.W.
E 5.11. S.
Service Water System F.W.S.
Feedwater System T.B.V.
Turbine Bypass Valve C.D.S.
Condensate System W.G.S.
Haste Gas System (Including Off-Gas)
S.J.A.E.
Stdam Jet Air Ejector C.W.S.
Circulating Water System R.C.S.
Reactor Clean Up System C.R.D.
Control Rod Drive R.D.S.
Reactor Depressurization System S. G.li.
Stack Gas lionitoring u.., soli
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April 11, 1978 Ifr James G Keppler Office of Inspection and Enforce =ent Region III US Nuclear Regulatory Consission 799 Roosevelt Road Glen Ellyn, IL 60137 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - RESPONSE.
TO IE BULLETIN 78-03 IE Bulletin 78-03 discusses the potential for accunulation of explosive gas nixtures in Boiling Water Reactor Off-Gas System Operations and requests that Consumers Power Company reviev and respond to specific areas of concern relat-ing to this system. The purpose of this letter is to provide the. requested response.
ITEM Review the operations and maintenance procedur?s related to the off-gas systes Include to assure proper operation in accordance with all design parameters.
in this reviev neasures you have taken or vill take to prevent inadvertent actions (such as are strikes) which might cause ignition of the mixture of gases contained in the off-gas piping.
RESPONSE
Big Rock Point Operating, Maintenance and Adninistrative procedures relating to the off-gas systes have been reviewed and, where necessary, appropriate precuations were added to preclude inadvertent ignition of potentially ex-plosive gases.
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/ ITE4 Review the adequacy of the ventilation of spaces and areas through khich off-
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i The reviev gas system piping containing explosive mixtures of gases pass.
should consider ventilation losses and off-normal off-gas system operation,
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such as lack of dilution steam, lost loop seals, blown rupture disks, by-
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passing recombiners and leakage of off-gas into isolated portions of systens.
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RESP 0 HSE A review of the design of the off-gas system at Big Rock Point indicates that there are two potential areas that could possibly be affected by off-Both These areas are the pipe tunnel and the radwaste area.
gas release.
areas are vell ventilated; the pipe tunnel having a flow of 5,000 cfm tocfm (de-lh,100 cfm (design) and the radwaste area from 1,500 cfm to T,c~
In order to reach an explosive concentration in these a eas, the hydrogen concentration vould have to exceed d and, based on tae ventilation sign).
I flow rates, this vould correspond to a hydrogen escape rate of 60 cfm and Since these 200 cfm for the radwaste area and pipe tunnel, respectively.
are significantly higher flow rates than nominally exist in the off-gas holdup line- (10. cfm), it is highly unlikely that the limit (s) can be exceeded.
The analysis deriving these flow rates assumes minimum design ventila-Note:
tion flow and uniform mixing.
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ITEM For those spaces and areas identified, describe what action you have taken or plan to take to assure that explosive mixtures cannot accumulate, that monitoring equipment vill varn of such an accumulation and that disposal of such mixtures vill be controlled without resulting in a demaging explosion.
RESPONSE
There are no plans to alter off: gas system or ventilation system design at There are no hydrogen detectors in either the radvaste area Big Rock Point.
or pipe tunnel and the only ventilation flow indication available in the con-However, because of trol roo= is ventilation supply and exhaust fan alar =s.
the extremely low potential for explosion based on both the analysis performed history with no in the previous response and Big Rock Point's long operatinb significant off-gas proble=s, it is concluded that current procedures, design and operation are adequate to preclude a damaging explosion.
ITE!
Loop seals are potential off-gas leakage paths following a pressure t'ransient in the off-gas system piping. Describe your design features to minimize and detect the loss of liquid froi:1 loop seals and describe operating procedures which assure prompt detection and rescal of the blown loop seals.
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RESPONSE
I There is no method available to ierify whether an off-gas loop seal is full.
pressure is nominally one to two ounces per Analysis has shown that off-ge f
square inch, necessitating e sour-inch loop seal to ensure scaling integrity.
Since all off-gas loop seal at Big Rock Point are approximately two feet or If a loop seal should fail longer, the possibility of seal failure is remote.
however, it vould auto =atically refill via moisture collection from within i
j the system and without any procedural action required.
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ZDI F.eview operating E.i emergency procedures to assure that your operating staff hr_s adequate guids. e to respond properly to off-gas system explosions.
F.ESPONSE 2ere a.e no Big F. ck PrM.nt Plant procedures that deal specifically with off-However, both the Operating Procedures and the Site gas system explosions.
Further, the Plant Emergency Plan ad h ess and adequately cover plant fires.
Operating Procedu es also address abnomal off-gas and stack gas releases as Based on this, it is cen-well as off-nomal procedures for other systems.
cluded that the required response to a postulated off-gas explosion is ade-quately addressed.
In su-mry, the operation and design of the off-gas system at Eig Rock Point has been reviewed for the potential of caintaining accumulations of explosive The review has produced no evidence that system design or operation Since further, and more de-gases.
should be citered based upon safety deficiency.
tailed, review in this area vill be conducted during the Systematic Evalua-tion Program (SEP), it is requested that any other required evaluation be coordinated with this effort.
( [.
William S Skibits:q (Signed)
William S Skibitsig Senior Licensing Engineer Director, Office of Nuclear Reactor Regulation CC:
Director, Office of Inspection and Enforcement G
82
3 th f cic k fHM Page 9 Section 9
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Rev I (3/19/62)
I 9.1.6 Monitoring and control 3
9.1.6.1 Protection agjinst excessive radioactive gas release rates is afforded by seEEl-continuous radiation monitors on the g
process off-gas system (as indicated in Section 7.12.
In the event that radiatign release rates exceed the continuous safe 3
discharge limit of' hL4 curies per secR, a valve in the off-gas At the line may be m nually closed to retain ine gases.
. higher level of -14 curies per second, this valve is closed automatically by a monitor signal. Valve closure requires plant shutdown and correction of the cause of high release.
After suitable decay, the retained gases, which have been
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held in the off-gas piping, are released and plant operation r esumed.
/b Continuous monitors on the stack provide a record pi both 9.1.6.2 total activity and niik25 -13 activity of all air and gases re-3; leased from the stack. A particulate sampler is also pro-vided on the stack to detect any significant release of radio-active particles. These monitors serve to indicate any changes or trends in release rates of radioactive gases or Means are
. particles, as well as total amounts released.
also provided for periodically measuring the concentrations
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of individual radioisotopes'so that they may be related to appropriate limits. (See Section 7.12.2) 9,.1. 7 Explosion Hazard h
A potential hazard in the off-gas system may, exist due to the presence of a stoichiometric mixture of hydrogen and cxygen.
Actually, the probability of a hydrogen-oxygen reaction occur 4g ring is very low, since the off-gas system is closed and no source of ignition or spark is present, and the gas is saturated with water vapor so no static spark should result.
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However, the system is designed to withstand the calculated pressures encountered due to such a reaction.
d.
jh 9.2 LIQUID WASTES i
,O 9.2.1 Sources and Quantitice The radioactivity of the liquid wastes is due to activation of 9.2.1.1 corrosion products formed in the nuclear steam supply system C
and the possible escape of fission products from fuel element cladding defects. The corrosion products result from the l,.
materials of construction of the system and consist of com-l pounds of iron, chronium, nickel, cobalt, zirconium, alu-minum, manganese, copper, etc. Radioactivity results from i.;}
neutron irradiation of these elements. Fission products, onThe j
the other hand, consist of a very wide range of elements.
total mixture of radioisotopes which can be present in the nucicar steam supply system at any particular time is thereforc-It can be characterized only in general by saying quite complex.
The total that most of the chemical elements can be present.
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ATTACHMENT II
ANALYSIS REQUIRED EY P7 Insulation to protect conduits and valve operators against a fire resulting from an oil leak at a Big Rock reactor recirculation pump is not needed.
Results of an analysis show that the temperature rise in the pump room and the duration of the abnormal temperatures are negligible. The temperature rise and duration are both directly related to how hot the conduit and valve operators ge'..
In addition, every item in the room absorbs heat. This further limits how hot the conduit and valve operators get.
Distance from a heat source also determines how much heat is absorbed by an item. The farther away from a heat source, the less heat that is absorbed.
The conduits and valve operators are approximately 50 feet from the recirculation pumps.
Ventilation through the room changes the air about once every 3-1/2 minutes.
This ventilation constantly takes heat away. Thus, any temperature rise in the room is quickly dissipated.
PVC cable has an ignition temperature of over 500 F.
Steel valves, while noncombustible, weaken at 1200 F.
Analysis indicates that a 50-square foot oil spill that is burning will raise the temperature.219 F above the ambient temperature. The temperature of uninsulated PVC cable will rise and may approach the room temperature. The cable may reach this temperature but cooling begins immediately due to ventilation.
A 3 gpm oil spray being burned raises the temperature in the room 222 F above the ambient temperrture. Again, the cabla temperature will rise and may approach the room cemperature.
Both of these situations assume an inoperative sprinkler system. However, when the sprinkler system operates the fire will be controlled and temperature rises will be drastically reduced.
Both situations produce temperatures well below the ignition temperature of PVC and the weakening temperature of steel.
In conclusion, insulation of conduits and valve operatros is not needed.
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