ML20235M977
| ML20235M977 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 02/21/1989 |
| From: | Hairston W GEORGIA POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 0594I, 594I, HL-330, NUDOCS 8902280522 | |
| Download: ML20235M977 (6) | |
Text
n_
~ Georg a hw Corrocy e
3 h Pm]muet Aw Atah f uor',; a 3G'.
=
Te:< pc,. 4 O y -i. 5 4
I M1 *GAJj' a Co-rP k f. s y
.m lw r
P:x.t n" ce b;;< '
fum nfv /d s a 5.2
( ${
{, 6 "'
r,l b
.h t'
W G. Hairston M s~
v" " "
HL-330 n e c ow,
X7GJ17-H120 February 21, 1989 U. S. Nuclear Regulatory Commission I
ATTN: Document Control Desk i
Washington, D.C.
20555 PLANT HATCH - UNITS 1, 2 l
NRC DOCKETS 50-321, 50-366 l
OPERATING LICENSES DPR-57, NPF-5 RESPONSE TO INSPECTION REPORT 08-38 Gentlemen:
In response to your letter of January 9,1989, and in accordance with the provisions of 10 CFR 2.201, Georgia Power Company (GPC) is providing the enclosed response to a Notice of Deviation identified in Inspection Report 88-38.
A copy of this response is being provided to NRC Region II for review.
In the enclosure, a transcription of the NRC deviation precedes GPC's response.
Should you have any questions in this regard, please contact this office at any time.
Sincerely, R).l. /b/
I^1-H. G. Hairston, III DLM/dm I
Enclosure:
Deviation 88-38-02 and GPC Response c:
(See next page.)
)
/)$
l
{
8902280522 890221 PDR ADOCK 05000321 Q
x U. S. Nuclear Regulatory Commission February 21,-1989 i
Page Two' j
c: Georaia Power Comoany Mr. H. C. Nix, Plant General Manager - Hatch Mr. L. T. ' Gucwa,- Manager Nuclear -Engineering and Licensing GO-NORMS U.
S'. Nuclear Reaulatory Commission. Washington. D. C.
Mr. L P. Crocker, Licensing Project Manager - Hatch U. S. Nuclear Reaulatory Commission. Region II Mr. M. L. Ernst,-Acting Regional Administrator Mr. J. E. Henning, Senior Resident Inspector - Hatch i
l l
ENCLOSURE 1 PLANT HATCH - UNITS 1 AND 2
'NRC DOCKETS 50-321 AND 50-366 OPERATING LICENSE DPR-57 AND NPF-5 DEVIATION 88-38-02 AND GPC RESPONSE DfyJ_ATION 88-38-02 Paragraph 7.5 of PUAR, Suppression Pool Temperature Monitoring, states that the suppression pool temperature monitoring system is required to ensure that the suppression pool is within the allowable limits set forth in the plant Technical Specifications.
It also states that the numbers and distribution of the pool temperature sensors shown in F1gure 7.5-1 (Note: 11 sensors are shown) provide the means for a reasonable measure of the bulk temperature at' suppression pool.
Contrary to the above, the bulk temperature or average temperature from 11 sensors stated in the PUAR was not used for Technical Specification, display at control room, and alarm setting at control room.
The licensee uses the bulk temperature from four sensors, one at 00, 900, 1800, and 2700 of suppression pool, for Technical Specification, display, and alarm setting.
The four sensors were not stated and qualified for purpose of suppression pool temperature monitoring stated in PUAR.
RESPONSE TO DEVIATION 88-38-02 Discussion During' the original design of the BHR/4 Mark I containment, a suppression pool bulk temperature limit of 95'F was established.
This limit assured that, for a DBA, the suppression pool temperature would not rise above 170*F and steam condensation would be assured.
Four temperature sensors, T48-N009A-D, (referred to as the N009 series) were installed in the suppression pool of these Mark I containments for monitoring purposes to ensure that the pool remains within the allowable limits set forth in the plants Technical Specifications.
The four sensors utilized for this monitoring at Plant Hatch are those discussed in the Deviation.
0594I HL-330 E-1
t
(
)
ENCLOSURE 1 -(continued)
DEVIATION 88-38-02 AND GPC RESPONSE Subsequent to the initial design-of the Mark I containments, it was determined tnat an enhanced suppression pool temperature monitoring system should be installed in all Boiling Water Reactor containment
{
systems to provide the necessary information for operator action to prevent severe vibrations during high pool temperature /high steam pressure condensation.
The eleven temperature elements, T48-N301 through N311 (referred to as the N300 series), delineated in Figure 7.5-1 of the subject Plant Unique. Analysis Report (PUAR) were installed to provide this information.
Both series have control room readouts as listed in the following table:
(
-===_-- -==-
=-- =____
ELEMENT RECORDER PANEL 1T48-N009A-D IT47-R611, R612
- 1Hil-P657,P654 1T48-N301A,B-IT47_R647 1Hil-P689 N311A,B 2T48-N009A-D 2T47-R626, R627
- 2H11-P657,P654 2T48-N301A,B_
2T47-R647 2Hil-P689 N311A,B All elements averaged and displayed on SPDS panels with visual alarm.
- Audible Alarm
_=-
As a result of this finding, Plant Hatch's Architect Engineer, Bechtel Power Corporation, General Electric and GPC Corporate licensing and engineering personnel have reviewed the requirements of NUREG 0661, NUREG 0783 and the Mark I Containment Program modifications at Plant Hatch.
0594I HL-330 E-2
d en ENCLOSURE 1 (continued)
DEVIATION 88-38-02 AND GPC RESPONSE Based on that review it was determined that a temperature limit for BWR suppression pools during SRV discharge was specified by the Nuclear Regulatory Commission (NRC) in NUREG-0783.
This limit was established 1
because of concerns about unstable steam condensation and associated high l
loads on the containment structure at high suppression pool temperatures, specifically the local pool temperature near the SRV discharge.
The concern was raised because of experiences in BWRs with prolonged SRV discharges without quencher devices.
Although all domestic
- BHRs, including Plant Hatch, now have quenchers, at the time the NRC established the local pool temperature limit, there was insufficient data i
available at high temperatures with quenchers to confirm that quenchers were effective in eliminating the unstable condensation loads.
It should be noted that since NUREG-0783 was issued, a significant amount of test data and analyses on unstable steam condensation was generated.
Most notably, scaling laws have been developed and confirmed for the discharge and condensation of steam in a suppression pool.
Also, the subscale data base has been extended over a range of pool temperatures up to saturation temperature with both straight pipe geometries and with quencher devices. The confirmation of scaling laws and the expanded data base now provide strong support for the elimination of the pool temperature limit for SRV discharge with quenchers.
The technical bases for the elimination of the local pool temperature limit are documented in i
NED0-30832.
This report was prepared under the sponsorship of the Suppression Pool Temperature Limit (SPTL) Committee of the BHROG and has been submitted to the NRC for review and approval.
The basic requirement of NUREG-0783 is that the suppression pool temperature be monitored to ensure that the calculated pool bulk temperature not exceed 200*F for postulated transient and accident conditions.
The models utilized to calculate the pool temperature assume a pool average temperature as an initial condition.
The Technical Specifications limit is therefore, the average pool temperature.
Georgia Power agrees that the four T48-N009 sensors do not technically read a j
true bulk pool temperature because of their location around the pool and i
their submergence.
Georgia Power also realizes that a true bulk pool i
temperature can not be determined from the eleven N300 series sensors due to their siallow submergence.
0594I HL-330 E-3 i
g
~
ENCLOSURE 1 (continued) i DEVIATION 88-38-02 AND GPC RESPONSE In order to provide a
more technically correct average pool' l
temperature, GPC proposes to utilize a representative average of the eleven N300 series sensors and the four N009 series sensors, i
Corrective steos which will be taken to avoid further deviation:
The Unit I and Unit 2 PUARs will be revised by December 31, 1989, to show that the suppression pool temperature monitoring system consists of the N300 series temperature sensors along with the N009 series sensors.
Administrative controls will be put in place by 5/01/89 to use a representative average previously described for Technical Specifications compliance.
Plant procedures will be revised. to reflect the average of the 15 temperature sensors for Technical Specifications compliance by 8/01/89.
4 I
05941 HL-330 E-4 i
_ _ - _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _