ML20115F191
| ML20115F191 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 04/15/1985 |
| From: | Cutter A CAROLINA POWER & LIGHT CO. |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| References | |
| NLS-85-125, NUDOCS 8504190438 | |
| Download: ML20115F191 (4) | |
Text
-
CASA Carolina Power & Light Company SERIAL: NLS-85-125 APR 151985 Director of Nuclear Reactor Regulation Attention:
Mr. D. B. Vassallo, Chief Operating Reactors Branch No. 2
. Division of Licensing United States Nuclear Regulatory Commission Washington, DC 20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS.1 AND 2 DOCKET NOS. 50-325 & 50-324/ LICENSE NOS. DPR-71 & DPR-62 CONTROL ROOM HABITABILITY
Dear Mr. Vassallo:
- INTRODUCTION By letters dated January 16,~ 1985 and February 21,1985, Carolina Power & Light Company (CP&L) committed to provide completion schedules for resolution of the control room 1/8-inch positive pressure concern and completion of the chlorine detection system modifications at Brunswick. - The purpose of this letter is to apprise you of the status and completion dates of these programs.
CHLORINE DETECTION As stated in our letter of February 21,1985, the Company intends to modify, as required, the current design of the chlorine detection system to assure that the air transport time from the chlorine detector to the isolation damper is greater than the isolation time from detection to isolaticn. This modification is scheduled to be completed by the end of
(-
the current Brunswick-1 refueling outage.'
'l/8-INCH POSITIVE PRESSURE By letter dated March 2,1983, CP&L committed to revise the existing periodic test acceptance criteria to quantify the positive pressure in the control room during operation of the Control Room Emergency Ventilation System. This procedure was revised as required. However, during performance of the periodic test on June 15,1984, the l
acceptance criteria of 1/8-inch water gauge positive pressure could not be achieved, although the test verified that a positive pressure was maintained as required by the Technical Specifications. At that time, the Company began a program to identify and f repair the major areas of air exfiltration.~ The most significant exfiltration path has been r-evaluated as.the control room floor penetrations and the associated cable seals. Other leakage paths, such as door seals and minor duct work leakage were minor contributors to Lthe exfiltration. Results of this program indicate that sealing of several thousand
. electrical cable penetrations located in the control and instrument panels would be required in order to more closely approach a 1/8-inch positive pressure. Approximately 8504190438 850415 7 PDR ADOCK 05000324!
F PDR g
411 Fayetteville Street
- P. o. Box 1551
- Raleign. N. C. 27602 4
- Mr. D. B. Vassallo P;g2 2 half of these cable penetrations are associated with each unit. It has been determined that sealing of these penetrations within the panels (many of which are congested with
- cables and internals) is not possible during power operation due to the risk of damaging
' electrical circuits associated with safety-related equipment. Therefore, achieving a control room positive pressure of 1/8-inch water gauge would require a series of modifications with.the control room floor cable sealing portion alone estimated to cost
$1.2 million dollars.
The Brunswick control room area was designed, constructed, and licensed for a slight control room positive pressure. A review of the Brunswick Control Room Habitability Evaluation, submitted in response to NUREG-0737, Item III.D.3.4, indicated that no credit was taken for the 1/8-inch positive pressure, and thus, its conclusions remain valid with provision for a slight positive pressure. Additionally, the calculated control room' dose, based on the Control Room Habitability Evaluation of the existing plant design under design basis accident conditions, is 0.415 rem whole body and 0.41 rem thyroid.
This is well below the 10 CFR 50 criteria of 5 rem whole body and 30 rem thyroid. Thus, any potential impact on radiological exposure of control room personnel would be minimal. As such, CP&L believes that the modifications necessary to achieve a 1/8-inch positive pressure in the control room are not justifiable on a cost / benefit basis, and would not result in a substantial increase in the overall protection of the public's health and satety.
In order to assure a slight positive pressure is maintained in the control room habitability -
area during operation of the Control Room Emergency Ventilation System, CP&L plans ~
to install permanent air pressure differential instrumentation within the habitability area. Differential pressure at the following diverse locations will be sensed (also see Figure 1):-
Pressure Differential Location No.
Area Location 1
Control Room East wall near interior entrance door 204 l
2 Control Room' West wall l
L 3
/
Electronic
' West wall near Equipment Room i stairway entrance door 215 4
Electronic West wall ne~ar i
Equipment Room 2 stairway entrance door 208 Installation of the air pressure differential instrumentation is scheduled to be completed by the end of 1985.
Based on the above, the Company has re-evaluated.the need and requirement to maintain a 1/8-inch water gauge positive pressure in the control room during operation of the Control Room Emergency Ventilatjon System and determined that maintaining a slight positive pressure in the control room will assure control room habitability. The mpdifications necessary to achieve a 1/8-inch positive pressure would not result in an increase in the overall protection of the public's health and safety that is commensurate with the cost. Therefore, CP&L believes that maintaining the control room at a positive t-i.
f i
~*
Mr. D. B. Vassallo q
Pega 3 pressure which is less than 1/8-inch is fully justified and will assure habitability as demonstrated in the Brunswick Control Room Habitability Evaluation.
CONCLUSION The required modifications to the chlorine detection system'will be completed by the end of the current Brunswick-1 refueling outage. Installation of permanent air pressure
. differential instrumentation within the habitability area and performance of periodic test to verify positive pressure in the control room are scheduled to be completed by the end of 1985.
\\
' Should you have any questions concerning this matter, please contact Mr. Sherwood R.
Zimmerman at (919) 836-6242.
Yours very trul A. B. Cutter - Vice%
President Nuclear Engineering & Licensing MAT /crs (1368 MAT)
. cc:-
Mr. L. W. Garner (NRC-BNP)
Dr. J. Nelson Grace (NRC-RII)
Mr. M. Grotenhuis (NRC) 4 2
L y
\\
v-ye y
y-vs,-+-
g--^--t--me ww-t-
-t-*y-'--v---
'iv-*-*--T 9 'r t"'+'le T-er'
'-w-s**
t'v er-t v -
- wevrf v't--
v-w-=r*vr-e--w
-'--w-w'+
't'--'
w Proposed Locations for Permanent Differential Pressure Instrumentation Location 2
,rY
.,-dr
.$5
=
- iw A-4
'i N ;mm-
_ W fe!:a:
T~
- = ! e,
j j
Location 4 s 'l[
r=1 '
l l
l l
Y ocation 3 L
@"$ '~:d "
=
e n m.o %
f c:1 crne.cs ico,riou s m.
a e
2-.
a o
a g yf-~ pp* Sj.
a g
o 2
a e,
a r
o j
l
'.x
.,,. a.
I
\\
E Location 1 FIGURE 1 4