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NOV 2 91978 MEMORANDUM FOR:
B. K. Grimes, Assistant Director for Engineering and Projects, DOR FROM:
E. L. Jordan, Assistant Director for Technical Programs, IE
SUBJECT:
REVIEW 0F RESPONSES TO IE BULLETIN 78-03 This memo completes our action on IE Bulletin 78-03, " Potential Explosive Gas Mixture Accumulations Associated with BWR Offgas System Operations. " Our actions included review of the responses from the operating BWR licensees and a review of the installed offgas system at each of the operating facilities in connection with the NRC commitment to Congressman Brooks in the response to the GA0 report on offgas explosions.
Individual plant details related to loop seals, rupture disks, ventilation of area and protection from ignition sources have been summarized for each operating facility and conclusions made.
Draft copies of the first eleven of these sumaries were informally given to Ronnie lo on November 1,1978 to facilitate timely review.
Pertinent facts from the enclosed sumaries were tabulated in order to further refine the information (Table 1).
From this tabulation, the summary assessments, and from the licensee responses, two recom-mendations appear to be justified.
These are (1) that NRC specify reactor shutdown in the event of an offgas pressure transient analogous to an uncontrolled hydrogen burn and reactor operation not be resumed until the offgas system is re-established in its normal operating condition; and (2) that NRC require upgrading the offgas systems to provide that all potential openings (unconfined loop seal vents and overpressure relief) be equipped with positive direct-action sensors to inform the operator that an offgas leak has occurred.
Our review identified certain other considerations that have a potential for becoming a problem or could improve protection against inadvertent ignition of hydrogen.
These are (1) mechanical vacuum pump and its separate pipeline which can involve this piping being CONTACT:
C. J. DeBevec, TP 49-28180
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B. K. Grimes 2
NOV 2 S 1978 filled and often isolated with explosive mixtures of hydrogen depending on individual plant features and operations that should be included in the overall evaluation; (2) extended reactor operation with recom-biners inoperable or bypassed can increase radioactive gas release rates through decreased holdup time and increase the possibility of hydrogen ignition due to it's presence in the entire offgas piping system; and (3) offgas piping color-code or otherwise uniquely identi-fied could reduce the likelihood of_ inadvertent operations leading to release or inadvertent ignition of hydrogen. We believe these items should be reviewed and an NRC position established on require-ments, as appropriate.
Items on which IE will perform followup inspections are identified in the last column of Table I.
These recommendations and enclosed supporting information are pro-vided for your consideration.
please contact Chuck DeBevec (28180) for additional information.
y ward.L.
Jordan, Assistant Director for e nical programs Divisi of Reactor Operations Inspection
Enclosures:
1.
Table 1 as described 2.
Summary Assessments as stated cc: w/encls.
N. C. Moseley, IE E. J. Brunner, RI F. J. Long, RII G. Fiore111, RIII G. L. 4%dsen, RIV J. L. Crews, RV L. H. Barrett, DOR R. Lo, D0R J. J. Rizzo, OMpA J
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_ _ _ TABLE 1 - SLW ARY OF OPERATING BWR OFFGAS SYSTEMS OTHER 5
l MAIN FEATURES SALIENT ITEMS CONCLUSIONS CCeNENTS hTARTUPI f
g OPERATIONS d
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QUAD yes yes yes Rechar NY yes yes OK fiO yes H
P R
l yes None CITIES 1&;,
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PILGRIM 1 yes yes yes lRechar V
yes 10 OK N0 i yes H
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BIG ROCK yes yes N0
!No V
NO NO OK NO yes H
P PM yes None
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P N0 i yes,' (i)
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, ms yes yes !
yes H
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7 H3NTICELLO ves No i ves AGG l NV NO l yes l OK NO l yes H
NOl NO yes None 8
BROWNS yes NO yes Rechar NY NO N0 OK NO yes H
P NO yes None l-FERRY 1,253 i
i 9l COOPER l yes l yes 'Recharl NY NO [
NO FP l NO yesl H
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! Ven yes yes 10!HATCil1&2
! NO yes yes Rechar! V NO l
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l 10 yes OK l
NO yes yes (m) l 11 PEACH yes NO yes A0G V
NO NO OK NO yes H
P NO l yes ! None BOTTCH 2&3 l
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12!DRESDEN2L3yes !yes l yes 'Rechar! V yes I NO l
OK l 10 l yes l H
l P
l R yes l Hone I NOG I
BRUNSWICK yes lyes yes 14 V
NO N0 OK NO yes H
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NA yes LOOP SEALS hechar' V yes NO OK NO yes H
P NO yes PROC 15 VEEMONT yes fic yes YA'iKEE
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page 2 TABLE 1 -
SUMMARY
OF OPERATING BWR OFFGAS SYSTEMS OTHER MAIN FEATURES SALIENT ITEMS CONCLUSIONS COMMENTS STARTUP OPERATIONS g
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ening through which the offgas system can vent. Consideration s1ould be given to changing to a permanent closure or to encase by piping to control the vented gas. 5. Since operation of the reactor can continue with the recombiners bypassed, we believe there is a significant potential for the accumulation of hydrogen in concentrations over four percent within the piping and equipment of the Rechar system. The licensee says he will not normally operate in such a mode. We believe that consideration of this should be included in the evaluation of the system.
Attachment:
Licensee Response to IEB 78-03 t
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Encicsure 2 B
SUMMARY
OF 0FFGAS SYSTEM DETAILS
.FOR PILGRIM UNIT NO. 1 A.
Main Features:
Operating SJAE with Rechar system; can.be bypassed with 30 minute holdup line.
Startup
- Mechanical vacuum pump and separate line.
B.
Salient Items:
1.
Loop Seals - Total of four; last one is in base of stack plenum.
- Two seals vent back to system; one controlled vent to radwaste; last one' vents directly into stack dilution flow.
Additional information is in Attachment 2.
2.
Rupture Disks - One rupture disk vents to building in case of overpressure in piping.
3.
Ventilation - All locations are ventilated.
- Air purge line is provided for maintenance.
4.
Protection Against Ignition Sources -
- Offgas piping no't color coded.
- Procedures include precautions against inadvertent ignition.
C.
Conclusions :
1.
The Region I Inspector has completed his followup inspection on IE Bulletin 78-03.
The inspection report (IR 50-293/78-22) includes the inspector's confirmation that the licensee performed the required action; a particular item regarding one loop seal will be re-examined during a future inspection.
2.
We believe that potential hydrogen accumulation can cccur within the mechanical v'acuum pump line system.
This potential source of hydrogen should be recognized in the promulgation of overall controls.
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'2 3.
We believe that consideration should be given to direct monitoring of loop seal integrity that vent to systems other than back to itself.
4.
Although the rupture disk is located in a ventilated area,
. we believe it represents a potentially sigaificant opening through which the offgas system can vent. We believe that consideration should be given to changing to a permanent closure or by containing the vented gas.
5.
The operating procedures were found to generally require-reactor shutdown if the recombiners were inoperable, however, operation could be continued by simply changing valves to bypass the Rechar-system and direct the offgas into the old 30 minute holdup line. We believe that consideration should be given to specifying limits on operations without
.the recombiners.
Attachments:
1.
Licensee Response to IEB 78-03 2.
Excerpt from IR 50-293/78-22 9
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SUMMARY
INFORMATION FOR MILLSTONE UNIT NO.1 The enclosed information describes in detail-the salient items and considerations related to features of the offgas system at Millstone Unit No, l.-
In addition, information on improvements made to the facility. is also included to provide a description of the system after its rehabilitation from the hydrogen. explosion that led to the issuance of IEB 78-03..We are not including any specific recom-mendations with this review summary, however, we would expect that any generic upgrading to be also applicable to this facility.
The enclosed information consists of the following items:
1.
Immediate Action Letter (IAL) dated December 14, 1977.
2.
Licensee response to IAL dated December 22, 1977.
3.
Region I analysis of licensee action.
4.
Licensee response to IEB 78-03.
5.
Licensee completes modifications and reports by letter dated April 21, 1978.
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SUMMARY
OF 0FFGAS SYSTEM DETAILS FOR BIG ROCK POINT
-A. Main Features:-
Operating SJAE with a'30-minute holdup line.
Startup
- Mechanical vacuum pump with a separate pipeline.
B. Salient Items:
1.
Loop Seals - Unit'has three;' firstLis a non-vented hardpiped drain back to main condenser; second is vented to mechanical vacuum pump pipeline with con-densate drain back to main condenser; third is vented to building-exhaust duct with condensate drain to open sump in radwaste.
In addition, there is a condensate drain from the base of stack to receiver tank in radwaste.
2.
Rupture Disks - There are no rupture disks remaining in the Big Rock Offgas system.
3.
Ventilation - All locations appear to be adequately ventilated.
4.
Protection Against Ignition Sources -
- Offgas piping is not color-coded.
- Procedures include precautions against inadvertent ignition.
C.
Conclusions :
1.
The Region III Inspector has completed his followup inspection on IE Bulletin 78-03.
The inspection report (IR 50-155/78-06) includes the inspector's finding of no items of noncompliance or deviations with the licensee response to the bulletin.
2.
We believe that potential hydrogen accumulation can occur within the mechanical vacuum pump pipeline.
This potential source of hydrogen should be recognized in the promulgation of overall controls.
3.
We believe that consideration should be given to direct monitoring of those loop seals which vent to systems other than back to itself.
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We note that this operating BWR does not-have an upgraded offgas system; rather, it uses its original 30-minute holdup system.. -Most of that piping system is : located underground -
for shielding purposes. -
Attachment:
Licensee Response to IES 78-03 5
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-ENCLOSURE 5
SUMMARY
OF OFFGA3 SYSTEM DETAILS
-FOR DUANE-ARNOLD A. Main Features:
Operating - ~SJAE with Rechar system that is hardpiped through the recombiners; charcoal filters can be bypassed.
Startup
-- Mechanical vacuum pump with a separate pipeline.
B.
Salient Items:
1.
Loop Seals - A total of five loop seals of which at the present time only three will automatically
.fsolate upon a 4 to 5 psig increase in system pressure. Commitment to include the other two loop seals in automatic isolation is pro-vided in licensee response to Bulletin 78-03.
2.
Rupture Disks - System includes a rupture disk that relieves pressure into piping which vents back to the main condenser..
3.
Area Ventilation - All locations are ventilated excepting for those areas identified in the licensee response to IEB 78-03.
The licensee response also gives a commitment to resolve the problem; the licensee told the IE Inspector that he plans to comp 1'te e
the change by the Spring of 1980.
4.
Protection Against Ignition Sources -
- The offgas piping is not color-coded.
Procedures include provisions against inadvertent ignition.
C.
Conclusions :
1.
The Region III Inspector has completed his followup inspection 4
on IEB 78-03.
The inspection report (IR 50-331/78-25) includes the inspector's confirmation that the licensee took the actions required in IEB 78-03.
The Inspector will continue followup on the ventilation item and carry it as an open item until the licensee completes tne modification.
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2' 2.
As consistent with other BWRs, potential hydrogen accumulation can occur within the mechanical vacuum pump pipeline. We believe that this potential source of hydrogen should also be' recognized in the overall evaluation of the offgas system..
3.
We believe that consideration should be given to direct.
monitoring of the integrity of loop seals which vent to systems other than back to itself.
4.
As indicated, we found that rupture disks do not vent into the building atmosphere.
5.
Since operation of the reactor cannot-be readily continued without the recombiners in service, we believe that no further specification is necessary-in this area.
Attachment:
Licensee Responses to IEB 78-03 o
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SUMMARY
OF 0FFGAS SYSTEM DETAILS FOR LACROSSE A.
Main Features:
Operating - SJAE with 10-minute holdup tank followed by recombiners and storage tanks with compressors.
Startup
- Mechanical vacuum pump and separate pipeline.
B.
Salient Items:
1.
Loop Seals - Two loop seals which vent to offgas line and drain back to main condenser. A number (approxi-mately seven) drain traps, which are level controlled, drain back to the main condenser.
2.
Rupture Disks - This system has no rupture disks; instead, overpressure protection is provided by relief valves. All eight relief valves are hardpiped back into the system.
3.
Area Ventilation - All areas are ventilated as described by licensee response to IEB 78-03.
4 4.
Protection Against Ignition Sources -
All offgas piping is painted with a silver color.
The, procedures include provisions against inadvertent ignition.
C.
==
Conclusions:==
1.
The Region III Inspector has completed his followup inspection on IEB 78-03. The inspection report (IR 50-409/78-04) includes i
the following:
"(closed) The inspector verified that licensee actions were as described in the response to the bulletin.
The licensee had prepared a draft of a procedure for response to a detonation in the offgas system.
It was being reviewed in accordance with the licensee's procedures and is scheduled to be issued shortly.
The inspector will review the procedure when received."
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acA can occt/6 withW the ~ mechanical vacuum pupp pipeline. '
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f which vent,to systems other tnan back into# ftself.
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are not ventid.-into the building atmosphere.' -
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This consideration should be includedrin'the 'overall evaluation '
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Attachment:
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SUMMARY
OF OFFGAS SYSTEM DETAILS FOR MONTICELLO-A.
Main Features:
Operating - SJAE with an Augmented Offgas System (A0G) which consists of recombiners, cryogenic distillation, i
compressors and storage tanks.
Startup
- Mechanical vacuum pump and separate pipeline.
B.
Salient Items:
1.
Loop Seals - There are two loop seals in the system; both vent to the suction side of the Booster jet-3 and drain to the receiver ~ tank in the SJAE I
room. Both of these seals are located.down-stream of the A0G.
2.
Rupture Disks - There are no rupture disks in this system;.
overpressure protection is provided by a total of three relief valves which vent via hardpipe back to the compressor suction. -
3.
Area Ventilation.- All areas are-ventilated.
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1 4.
Protection Against Ignition Sources -
- Offgas pipi1g is not color-coded. All valves in t1e system upstream of the-l recombiners were equipped with brass i
4 seats to reduce potential ignition sources.
Procedures include provisions against inadvertent ignition sources.
4 C.
==
Conclusions:==
4 1.
The Reg, ion III Inspector has completed his followup inspection on IEB 78-03. The inspection report (IR 50-263/78-07) includes the inspector's verification that the licensee
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performed the required actions without noncompliance or deviation.
2.
Potential hydrogen accumulation can occur within the mechanical-vacuum pump pipeline and this should be recognized in the 4
overall evaluation of the system.
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2 3.
We find no' apparent weakness with the system loop seals or overpressure protection.
4.
Operation of the reactor is not permitted noramily with recombiners inoperable or bypassed. However, a piping connection, which is blank-flanged, is provided that would permit operation without the recombiners in service but with the blank-flange removed.
Attachment:
Licensee Response to IEB 78-03 e
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SUMMARY
OF 0FFGAS SYSTEM DETAILS FOR BROWNS FERRY UNIT NOS. 1, 2, AND 3 A.
Main Features:
Operating
.Three stage SJAE with Rechar. system that is hard-piped through the recombiner; charcoal filters can be bypassed.
Startup
- Mechanical vacuum pump with a separate pipeline.
B.
Salient Itens:
1.
Loop Seals - As d'escribed in the licensee response to IEB-78-03, condensate is removed from the offgas system either by hard-piped drains back to the main condenser or by loop seal piping s
which incorporates an automatic isolation valve.
These automatic isolation valves are tripped by overpressure that would accompany a hydrogen detonation.
2.
Rupture Disks - There are no rupture disks or relief valves provided in this system at any Unit.
3.
Area Ventilation - All areas are considered to be ventilated.
4.
Protection Against Ignition Sources -
- Although the offgas system piping is not color-coded, the piping is being red-metal-tagged, with tags carrying the legend "Offgas Pipe - May Contain Hydrogen -
No Hot Work." The procedures include provisions against inadvertent ignition sources.
C.
Conclusions :
1.
The Region II Inspector has completed his followup inspection on IEB 78-03.
The inspection report (IR 50-259/78-17, 50-260/78-18,50-296/78-16) includes the inspector's verification that the required actions in the Bulletin had been taken by the licensee.
2.
Potential hydrogen accumulation can occur within the icechanical vacuum pump pipeline and this should be included in the overall evaluation of the system.
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3.- We believe that consideration should be given to providing direct monitoring of the integrity of.all loop seals.
4.
Since the system overpressure protection is apparently provided by venting through the loop seals and subsequent automatic isolation, the consideration with monitoring loop seals (as indicated above) is particularly important.
I 5.
Since operation of the reactor cannot be continued without the recombiners in service, we believe that no further speci-fication is necessary. in this area.
t Atta'chment:
Licensee Response to IEB 78-03 l
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SUMMARY
OF-0FFGAS SYSTEM DETAILS FOR COOPER' A.
Main Features:
Operating - Two stage SJAE and 30-minute holdup line with Rechar system which can be readily bypassed.
Startup
- Mechanical vacuum pump with separate pipeline.
B.
Salient Items:
1.
Loop Seals - As described in the licensee response'to IEB 78-03 the six loop seals drain to a sealed sump which is vented to the Elevated Release Point (ERP).
In addition, there are condensate drains which are hard-piped back to.the system and eventually to the main condenser hotwell.
2.
Rupture Disks - There are no rupture disks or relief valves provided; overpressure relief is apparently through the loop seals.
3.
Area Ventilation - All areas are considered to be ventilated with the possible exception of the offgas tunnel; this is identified in the licensee response to IEB 78-03.
4.
Protection Against Ignition So'urces -
- Although the offgas piping is not color-coded, most of the system piping is painted purple.
The procedures do include provisions to protect against inadvertent ignition.
C.
Conclusions :
1.
The Region IV Inspector has completed his followup in:pection on IEB 78-03. The inspection report (IR 50-298/78-08) includes the inspector's verification that the licensee had taken the actions required in the Bulletin.
The inspector will confirm the licensee's resolution of the ventilation of the piping chase identified in the licensee response to IEB 78-03.
2.
Potential hydrogen accumulation can occur within the mechanical vacuum pump pipeline and this should be included in the overall evaluation of the system.
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2 3.
We believe that consideration should be given to providing direct monitoring of the integrity of all loop seals, 4.
Since the system overpressure protection is apparently pro-vided by venting through the loop seals, the above consideration with monitoring loop seals is of direct importance.
In addition, we believe that consideration should be given to providing isolation valves, which are automatically closed on overpressure, on all loop seals.
5.
Since operation of the reactor can be continued with the recombiners bypassed, we believe there is a significant potential for a damaging hydrogen explosion in view of the evidence of migration of catalyst.
We believe that consideration should be given to defining and specifying recombiner operability requirements.
Attachment:
Licensee Response to IEB 78-03 l
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' Enclosure 10
SUMMARY
OF 0FFGAS SYSTEM DETAILS FOR HATCH UNITS 1 AND 2 A.
Main Features:
Operating - Three stage SJAE with Rechar system that is hard-piped through the recombiners; the charcoal filters-can be bypassed.
Startup
- Mechanical vacuum pump with a separate pipeline.
B.
Saltent Items:
1.
Loop Seals - There are two loop seals that vent to the building environment in case of system overpressure.
In addition there are hard-piped drains which collect and return condensate to the system.
2.
Rupture Disks - There are no rupture disks used in the Hatch offgas system.
Two relief valves are provided for overpressure protection; these vent back into the system.
3.
Area Ventilation - All areas may be ventilated, however, there is some question on how well adequate ventilation can be ascertained.
There appears to be a lack of adequate radiation monitoring..cither in the form of Continuous Air Monitoring (CAM) or Area Radiation Monitoring (ARM), to readily detect evidence of a leaking offgas system.
In particular, i
the IE Inspector identified areas which have no CAM or ARM equipnent.
These areas include the hydrogen sampler area, offgas tunnel, preheater/recombiner room, cooler-condenser / moisture separator room which also contains the loop seals.
4.
Protection Against Ignition Sources -
- Although the offgas piping is not color-coded most of it is painted white.
Procedures do include provisions against inadvertent ignition.
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2 C.
==
Conclusions:==
1.
The Region II Inspector has canpleted his followup inspection on IEB 78-03.
The inspection report (IR 50-321/78-24 and.
50-366/78-33) includes the inspector's verification that the licensee took the actions required by the Bulletin.
The inspector is carrying an open item on the licensee commit-ment for preparing an emeraency procedure to handle offgas system explosions.
In addition, the inspector is reporting offgas system information.in IR 50-321/78-33 and 50-366/78-41 to provide the supplemental details associated.with the IE assessment.
2.
Potential hydrogen accumulation can occur within the mechanical vacuum pump pipeline and this should be included in the overall evaluation of the system.
3.
We believe that consideration should be given to providing direct monitoring of the integrity of all loop seals.
4.
We see no problem with the overpressure provisions, however, we believe that the provisions for monitoring offgas leakage via CAM and ARM systems to be considerably less than desirable.
5.
Since the operation of the reactor cannot be continued without the recombiners in service, we believe that no further specification is necessary in this area.
Attachment:
Licensee Response to IEB 78-03 i
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, 1
SUMMARY
OF 0FFGAS SYSTEM DETAILS PEACH BOTTOM UNIT NOS. 2 AND 3 ~
A.
Main Features:
Operating - Two ' stage SJAE with~ redundant recombiners using old holdup volume for delay.
Startup
- Mechanical vacuum pump with a separate pipeline.
B.
Salient Items:
1.
Loop Seals - As described by licensee response to IEB 78-03, there are three loop seals which drain to clean rad waste. There are other condensate drains in the system that are valved normally closed.
2.
Rupture Disks - There are no rupture disks or relief valves provided in the system.
3.
Area Ventilation - All areas are considered to be ventilated.
4.
Protection Against Ignition Sources -
- Offgas piping is not color-coded.
Procedures include provisions against inadvertent ignition.
j C.
==
Conclusions:==
l.
The Region ! Inspector has completed his followup inspection on IEB 78-03.
The inspection report (IR 50-277/78-25 and 50-278/78-30) includes the inspector's verification that the required actions in the Bulletin had been taken by the licensee.
2.
Potential hydrogen accumulation can occur within the mechanical vacuum pump pipeline and this should be included in the overall evaluation of the system.
3.
We believe that consideration should be given to providing direct monitoring of all loop seals.
4.
Since the system overpressure protection is apparently pro-vided by venting through the loop seals and at the end of the holdup volume (impacting the HEPA filter), the above consideration with direct monitoring of loop s' als is of e
d direct importance.
2 5.
With blank-flanging of the recombiner bypass line, operation of the reactor would not be continued without the recombiners
.in service. We believe no further specification is necessary-in this area as a result.
Attachment:
. Licensee Response to IEB 78-03 e
} 2
SUMMARY
OF OFFGAS SYSTEM DETAILS FDR DRESDEN UNIT-NOS. 1, 2, AND 3 A.
Main Features:
Operating: -Unit 1 - Two stage SJAE with 30-minute holdup line.
A Rechar System is installed and inservice-operation awaits NRC review and approval of a licensee proposed change in related specifications.
-Unit 2&3 - Three stage SJAE with Rechar System which can be bypassed to use holdup line.
Startup:
Each unit has a mechanical vacuum pump with a separate pipeline.
B.
Salient Items:
l.
Loop Seals: Unit 1 - There are three loop seals with the 30-minute holdup system; all are hard-piped back to the main condenser. An additional condensate drain is. associated with the Rechar system.
Unit 283 - There are four loop seals which drain to the turbine building equipment drain or to the radwaste receiver tank.
2.
Rupture Disks - Each unit system has two rupture disks for overpressure relief.
Unit I uses an in-series relief valve for containing the rupture disk discharge; while Units 2&3 have not yet, but plan to incorporate an in-series relief valve. All relief discharges, excepting the one back to the main condenser, are to the building atmosphere.
3.
Area Ventilation - All areas are considered to be ventilated with conditions as described in the licensee response to IEB 78-03.
4.
Protection Against Ignition Sources -
- Offgas piping is not color-coded.
Procedures do include precautions against inadvertent ignition sources.
l l
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C.
==
Conclusions:==
1.
The Region III Inspector has canpleted his followup inspection.
on IEB 78-03.
Theinspectionreport(IR 50-010/78-25, 50-237/78-22, 50-249/78-24) includes the inspector's verification that the licensee had taken the actions required in the Bulletin.
In addition, particular actions taken by the licensee are described in the inspection report; an excerpt of which is attached.
2.
Potential hydrogen accumulation can occur within the mechanical vacuum pump pipeline and this should be included in the overall evaluation of the system.
3.
We believe that consideration should be given to providing direct nonitoring of the integrity of all loop seals.
4.
Because a blown rupture disk represents a significant opening in the offgas system, we believe consideration should be given to changing to a pennanent closure or containing the vented gas by relief valve discharge back into the system.
5.
Since operation of the reactor can continue with the recombiners inoperable or bypassed, we believe that the potential for accumulation of hydrogen in the system is significant.
This consideration should be included in the overall evaluation of the of fgas sys tem.
4
Attachment:
q 1.
Licensee Response to IEB 78-03 j
2.
Excerpt from IR 50-010/78-25 et al 5
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l.
... 3
SUMMARY
INFORMATION FOR HUMBOLDT BAY The operational status of this BWR is not clear at the present time due to licensing considerations with its seismic design provisions.
The enclosed licensee response to IEB 78-03 generally reflects this status of uncertainty.
In view of this situation we believe that any assessment of the offgas system at this time would be unwarranted.
Therefore, if and when this plant is again expected to return to operations, we would plan to include an assessment of their offgas system at that time.
Region V is carrying the inspection of the licensee's response to IEB 78-03 as an open item (as reported in IR 50-133/78-10); completion of this inspection and our assessment of the system will follow licensing approval of return to operations.
Attachment:
Licensee Response to IEB 78-03 e
a
. w Enclosure ~14
SUMMARY
OF 0FFGAS SYSTEM DETAILS FOR BRUNSWICK UNIT NOS. 1 AND 2 A.
Main Features:
Operating - SJAE with 30-minute holdup line. An A0G system with recombiners, compressors, cryogenic distillation and storage tanks has been installed but is not operational. When attempts were made to bring the A0G into operation internal detonation of hydrogen occurred.
The licensee states that approximately fifteen such detonations occurred up to the present time.
Startup
- Mechanical vacuun. pump with a separate pipeline.
B.
Salient Items:
1.
Loop Seals - As described in the licensee response to IEB 78-03, there are a total of 15 loop seals, of which 13 are located in the stack filter house and one in each reactor building.
The 13 in the stack filter house are made up of three from each Unit holdup volume, three from the mechanical vacuum pump lines, three from the HEPA filters and one from the stack sampler.
In addition, each Unit has two condensate drains from the SJAE condensers back to the main condenser.
2.
Rupture Disks - There are no rupture disks or relief valves in the system.
3.
Area Ventilation - As described in the licensee response to IEB 78-03, all areas are considered to be ventilated excepting certain valve pits.
4.
Protection Against Ignition Sources -
- Offgas piping is not color-coded.
Pro-cedures include precautions against inadvertent ignition.
C.
==
Conclusions:==
1.
The Region II Inspector has completed his inspection on IE Bulletin 78-03. The inspection report (IR 50-324/78-18, 50-325/78-18) includes the inspector's intention to review modifications when they are completed.
An excerpt from that report is, attached, t
~
2 2.
Potential hydrogen accumulation can occur within-the mechanical vacuum pump pipeline and this should be included in the
. overall evaluation of the system.
3.
We believe that consideration should be given to providing direct monitoring of the integrity of all loop seals.
4.
Because system overpressure relief is apparently provided by venting through the loop seals, the above consideration on loop seal monitoring is of direct importance.
5.
Since operation of the reactor is presently with use of the original holdup volume, consideration of the appropriate requirements with the A0G should be included at the time operating approval is given to the licensee.
Attachments:
1.
Licensee Response to IEB 78-03 2.
Excerpt from IR 50-324/325/78-18 t
e I
e 4
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Enclesure 15
SUMMARY
OF 0FFGAS SYSTEM DETAILS FOR VERMONT YANKEE A.
Main Features:
Operating - Two stage SJAE with Rechar System which cannot be bypassed without removal of a blank flange.
Flow through the Rechar system is provided by a vacuum pump at the stack.
Startup
- Mechanical vacuum pump with separate pipeline.
4 8.
Salient Items:
f 1.
Loop Serls - There are a total of five loop seals; one drains back to the main condenser, two in the Rechar system drain to a level-controlled drain tank, and two at the holdup volume drain to the rad-waste system.
2.
Rupture Disks - One rupture disk is used in the system; overpressure vents to the offgas pipe tunnel in the turbine building.
3.
Area Ventilation - All areas are considered to be ventilated.
With offgas system operation at a vacuan, air leakage is into the system.
4.
Protection Against Ignition So'urces -
- Offgas piping is not color-coded.
Procedures include precautions against inadvertent ignition.
C.
==
Conclusions:==
l.
The Region I Inspector has completed his followup inspection on IEB 78-03.
The inspection report (IR 50-271/78-21) includes the inspector's verification that the licensee had taken the action required in the Bulletin.
The inspector is carrying an open item on the licensee conmitment to expand his fire protection procedural provisions against inadvertent ignitions to the SJAE room an.1 related areas.
2.
Procedures require purging of the mechanical vacuum pump pipeline after startup, thus minimizing any potential hydrogen accumulation in this line when not in use.
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2 3.
We believe 'that consideration should be given to providing direct monitoring of the integrity of loop seals which drain to any other system.
4.
Although the rupture disk -is located in a ventilated area, we believe it represents a potentially significant opening through which the offgas system'can vent.
Consideration should be given to changing to a permanent closure or by containing the vented gas.
5.. With blank-flanging of the bypass line, operation of the reactor would not be continued without the recombiners in service. We believe no further specification is necessary in this area.
Attachment:
Licensee Response to IEB 78-03 O
e t
m
i 6
SUMMARY
OF 0FFGAS SYSTEM DETAILS FOR OYSTER CREEK A.
Main Features:
Operating - SJAE with Rechar system which can be readily bypassed.
The Rechar system is incorporated in the old holdup system just downstream of the stack, thus the original holdup volume is always in use.
Startup
- Mechanical vacuum pump with separate pipeline.
B.
Salient Items:
1.
Loop Seals - One loop seal is located in the old system and is drained to a sump at the base of the stack.
Other condensate drains are made through level-controlled traps as described in the licensee response to IEB 78-03.
2.
Rupture Disks - There are no rupture disks in the system.
A relief valve is provided downstream of the recombiner-condenser and is discharged to the Offgas building ventilation duct.
3.
Area Ventilation - All areas are considered to be ventilated.
4.
Protection Against Ignition Sources -
- Offgas piping of the Rechar system has been painted a single color.
Procedures include precautions against inadvertent ignition.
C.
==
Conclusions:==
1.
The Region I Inspector has completed his followup inspection on IEB 78-03. The inspection report (IR 50-219/78-25) includes the inspector's verification that the licensee had taken the action required in the Bulletin. The inspector is carrying an open item on the ventilation tests that the licensee commits to performing in his response to IEB 78-03.
2.
Potential hydrogen accumulation can occur within the mechanical vacuum pump pipeline and this should be included in the overall evaluation of the system.
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2 3.
We believe that consideration should be given to providing direct monitoring of the integrity of the loop seals.
4.
We find no apparent weakness with the overpressure provisions in the offgas system.
5.
Since operation of the reactor can continue with the recom-biners inoperable or bypassed, we believe that the potential for accumulation of hydrogen in the system is significant.
This consideration should be included in the overall evaluation of the offgas system.
Attachment:
Licensee Response to IEB 78-03 s
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. 7 SUM 4ARY OF 0FFGAS SYSTEM DETAILS FOR NINE MILE POINT UNIT NO. I
~A.
Main Features:
Operating - Two stage SJAE with Rechar system which-can be bypassed; this is administrative 1y not allowed.
Flow through the Rechar system is provided by vacuum pumps at the stack.
Startup
- Mechanical vacuum pump with a separate pipeline.
8.
Salient Items:
1.
Loop Seals - All loop seals are hard-piped to a drain tank which is drained by a level-controlled valve back to the main condenser.
2.
Rupture Disks - There are no rupture disks or relief valves in the system.
3.
Area Ventilation - All areas are considered to be ventilated 4.
Protection Against Ignition Sources -
- The Offgas system piping is not color-coded.
Procedures do include precautions against inadvertent ignition.
C.
==
Conclusions:==
1.
The Region I Inspector has completed his followup inspection on IEB 78-03.
The inspection report (IR 50-220/78-16) includes that the inspector had no further questions on the licensee's response to the Bulletin.
2.
Potential hydrogen accumulation can occur within the mechanical vacuum pump pipeline and this should, be included in the i
overall evaluation of the system.
i
'3.
We find no apparent weakness with the hard-piped loop seals which drain condensate back to the main condenser nor with the provisions for overpressure release.
4.
Since operation of the reactor can continue with the recom-biners inoperable or bypassed, although not operationally pennitted, we believe that the potential for accumulation of hydrogen in the system is significant.
This consideration I
should be included in the overall evaluation of the system.
Attachment:
Licensee Response to IEB 78-03
4 o
Encicsure 18
SUMMARY
OF 0FFGAS SYSTEM DETAILS FOR J.A. FITZpATRICK A.
Main Features:
Operation - Three stage SJAE with Rechar system which can be readily bypassed. Operations below about 30% rated power uses the 30-minute holdup volume.
Startup
- Mechanical vacuum pump with a separate pipeline.
B.
Salient Items:
1.
Loop Seals - As described in the licensee response to IEB 78-03, all potentially vented loop seals were removed and replaced with hard-piped drains to drain tanks, which subsequently drain back to the main condenser through a level-controlled valve.
2.
Rupture Disks - There are'no rupture disks or relief valves in the system.
3.
Area Ventilation - All areas are considered to be ventilated.
4.
protection Against Ignition Sources -
- Offgas system piping is not color-coded.
Procedures,do include precautions against inadvertent ignition.
C.
Conclusions :
1.
The Region I Inspector has completed his followup inspection on IEB 78-03.
The inspection report (IR 50-333/78-19) includes the inspector's verification that the licensee had taken the action required in the Bulletin.
2.
potential hydrogen accumulation can occur within the mechanical vacuum pump pipeline and this should be included in the overall evaluation of the system.
3.
We find no apparent weakness with the hard-piped loop seals which drain condensate back to the main condenser nor with the provisions for overpressure release.
I l
l
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v
-2 4.
Since operation of the reactor is continued with the recombiners inoperable or bypassed, we believe that-the potential for
- accumulation of hydrogen in the system is significant.
This consideration should be included in the overall evaluation of the system.
Attachment:
Licensee Response to IEB 78-03 I
e P