ML20028C424: Difference between revisions
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| number = ML20028C424 | | number = ML20028C424 | ||
| issue date = 06/29/1978 | | issue date = 06/29/1978 | ||
| title = Responds to Items 2 & 3 of IE Bulletin 78-03, Potential Explosive Gas Mixture Accumulations Associated W/Bwr Offgas Sys Operations, Per | | title = Responds to Items 2 & 3 of IE Bulletin 78-03, Potential Explosive Gas Mixture Accumulations Associated W/Bwr Offgas Sys Operations, Per .Ventilation Is Sufficient to Preclude Accumulation of Explosive Hydrogen Concentration | ||
| author name = Wallace J | | author name = Wallace J | ||
| author affiliation = IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT | | author affiliation = IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT | ||
| Line 12: | Line 12: | ||
| case reference number = FOIA-82-545, REF-SSINS-6820 | | case reference number = FOIA-82-545, REF-SSINS-6820 | ||
| document report number = IEB-78-03, IEB-78-3, NUDOCS 8301100110 | | document report number = IEB-78-03, IEB-78-3, NUDOCS 8301100110 | ||
| title reference date = 04-28-1978 | |||
| package number = ML20027A594 | | package number = ML20027A594 | ||
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE, UTILITY TO NRC | | document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE, UTILITY TO NRC | ||
| Line 18: | Line 19: | ||
=Text= | =Text= | ||
{{#Wiki_filter:. | {{#Wiki_filter:. | ||
A M. . b, | A M.. b, IOWA Etscraic ItonT AND Powsn COMPANY General CV5ce CanAn RApros. IOWA ane 29, in8 Vg 3, | ||
VICE PRESIDENT-GENER/. DON Mr. James G. Keppler, Director Office of Inspection and Enforcement Region III U. S. Nuclear Regulatory Commission 799 Roosevelt Road-Glen Ellyn, IL 60137 Re: | |||
Duane Arnold Energy Center IE Bulletin 78-03 | |||
==Subject:== | ==Subject:== | ||
Potential Off-Gas System Gas Accumulation Additional Response Information | Potential Off-Gas System Gas Accumulation Additional Response Information 3 | ||
File: | |||
A-101a | |||
==Dear Mr. Keppler:== | ==Dear Mr. Keppler:== | ||
This letter is in response to IE Bulletin 78-03, items 2 and 3 as previously discussed in our {{letter dated|date=April 28, 1978|text=April 28, 1978 letter}}. | |||
This letter is in response to IE Bulletin 78-03, items 2 and 3 as previously discussed in our April 28, 1978 letter. | ITEM 2 We have reviewed the adequacy of' ventilation for spaces and areas containing offgas system piping. | ||
ITEM 2 We have reviewed the adequacy of' ventilation for spaces and areas containing offgas system piping. Based on this review, we have verified that under normal operating conditions the ventilation is sufficient to preclude accumulation of an explosive concentratio of hydrogen. | Based on this review, we have verified that under normal operating conditions the ventilation is sufficient to preclude accumulation of an explosive concentratio of hydrogen. | ||
We have also verified that for ventilation losses during nor=al offgas system operation, the system design precludes the accumu-lation of an explosive mixture of hydrogen. | We have also verified that for ventilation losses during nor=al offgas system operation, the system design precludes the accumu-lation of an explosive mixture of hydrogen. | ||
During our review of off-normal offgas system operation we have identified | During our review of off-normal offgas system operation we have identified one condition which could lead to accumulation of an explosive mixture. | ||
During normal operation offgas is diluted in In..the event of loss of dilution steam flow valve MO-4151 is automatically shut, isolating the jet compressor. | During normal operation offgas is diluted in jet compressor 1S-111. | ||
This causes a pressure transient in the system which actuates several pressure switches which in turn automatically close the isolation valves on the system loop seals. | In..the event of loss of dilution steam flow valve MO-4151 is automatically shut, isolating the jet compressor. | ||
This causes a pressure transient in the system which actuates several pressure switches which in turn automatically close the isolation valves on the system loop seals. | |||
Two loop seals are located upstream of MO-4151. | |||
In the event that insufficient water is available in one of.the loop seals upstream of MO-4151, the loop seal may blow before sufficient 8301100110 821207 PDR FOIA HIATT82-545 PDR l | |||
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3 Page-2 June 2 9, 1978 r | |||
June 2 9, 1978 r | . A pressure to actuate the.~ system p,ressure switches. develops. | ||
Under w | |||
these conditions undiluted..offgas would be discharged to the turbine building equipment drain cump 'or the offgas retention building equipment drain sump. | |||
Considering normal ventilation flow, the average hydroSen''cbacentration in each area would be 16.7% and 13.0% by'' volume respectively. | |||
s We have identified no other condition which could result in accumulation of sufficient hydrogen to form an explosive mixture. | s We have identified no other condition which could result in accumulation of sufficient hydrogen to form an explosive mixture. | ||
Our | Our review considered loss of ventilation flow, loss of dilution st> | ||
ost loop seals, blown rupture disks, and leakage of of Anto isolated portions of the system. 4 Bypassing the recom'.ainers was not considered as this is not applicable to the DAEC design,. | |||
s ITEM 3 s | |||
To assure that the condition identified above does not occur we are planning the following system design changes: | |||
~ | |||
1. | 1. | ||
We will install water fill lines to al1 loop seals which presently do'not have fill capability. | We will install water fill lines to al1 loop seals which presently do'not have fill capability. | ||
2. | |||
We will modify the system logics to automatically isolate the two loop seals' upstream of MO-4151 upon closure of MO-4151,. | |||
' \\. | |||
's very truly you s, | |||
- -~ % | |||
1 J. | |||
Vice President-Generation | A. Wallace | ||
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e JAW /RAA/nf | ' '' [ ', | ||
cc: | Vice President-Generation | ||
S. Nuclea.r Regulatory Commission Office of Inspel: tion and Enforce::ient | ~ | ||
e JAW /RAA/nf | |||
Division of Reactor Opsrations Inspection | ,'i d | ||
Washington, ,D. C. | / | ||
cc: | |||
s | U. S. Nuclea.r Regulatory Commission Office of Inspel: tion and Enforce::ient Division of Reactor Opsrations Inspection Washington,,D. | ||
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Latest revision as of 18:59, 20 December 2024
Text
.
A M.. b, IOWA Etscraic ItonT AND Powsn COMPANY General CV5ce CanAn RApros. IOWA ane 29, in8 Vg 3,
VICE PRESIDENT-GENER/. DON Mr. James G. Keppler, Director Office of Inspection and Enforcement Region III U. S. Nuclear Regulatory Commission 799 Roosevelt Road-Glen Ellyn, IL 60137 Re:
Duane Arnold Energy Center IE Bulletin 78-03
Subject:
Potential Off-Gas System Gas Accumulation Additional Response Information 3
File:
A-101a
Dear Mr. Keppler:
This letter is in response to IE Bulletin 78-03, items 2 and 3 as previously discussed in our April 28, 1978 letter.
ITEM 2 We have reviewed the adequacy of' ventilation for spaces and areas containing offgas system piping.
Based on this review, we have verified that under normal operating conditions the ventilation is sufficient to preclude accumulation of an explosive concentratio of hydrogen.
We have also verified that for ventilation losses during nor=al offgas system operation, the system design precludes the accumu-lation of an explosive mixture of hydrogen.
During our review of off-normal offgas system operation we have identified one condition which could lead to accumulation of an explosive mixture.
During normal operation offgas is diluted in jet compressor 1S-111.
In..the event of loss of dilution steam flow valve MO-4151 is automatically shut, isolating the jet compressor.
This causes a pressure transient in the system which actuates several pressure switches which in turn automatically close the isolation valves on the system loop seals.
Two loop seals are located upstream of MO-4151.
In the event that insufficient water is available in one of.the loop seals upstream of MO-4151, the loop seal may blow before sufficient 8301100110 821207 PDR FOIA HIATT82-545 PDR l
m
- T i,f .
t-i --,
. {.
's
- Mr.' Keppler 1
3 Page-2 June 2 9, 1978 r
. A pressure to actuate the.~ system p,ressure switches. develops.
Under w
these conditions undiluted..offgas would be discharged to the turbine building equipment drain cump 'or the offgas retention building equipment drain sump.
Considering normal ventilation flow, the average hydroSencbacentration in each area would be 16.7% and 13.0% by volume respectively.
s We have identified no other condition which could result in accumulation of sufficient hydrogen to form an explosive mixture.
Our review considered loss of ventilation flow, loss of dilution st>
ost loop seals, blown rupture disks, and leakage of of Anto isolated portions of the system. 4 Bypassing the recom'.ainers was not considered as this is not applicable to the DAEC design,.
s ITEM 3 s
To assure that the condition identified above does not occur we are planning the following system design changes:
~
1.
We will install water fill lines to al1 loop seals which presently do'not have fill capability.
2.
We will modify the system logics to automatically isolate the two loop seals' upstream of MO-4151 upon closure of MO-4151,.
' \\.
's very truly you s,
- -~ %
1 J.
A. Wallace
,s
' [ ',
Vice President-Generation
~
e JAW /RAA/nf
,'i d
/
cc:
U. S. Nuclea.r Regulatory Commission Office of Inspel: tion and Enforce::ient Division of Reactor Opsrations Inspection Washington,,D.
C.
20555 N
T s
s l
,s
%s 4
g N
\\
U g
(
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, s i
+e
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