ML20079M934
| ML20079M934 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 01/25/1984 |
| From: | Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.E.4.2, TASK-TM NUDOCS 8401270474 | |
| Download: ML20079M934 (5) | |
Text
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PHILADELPHIA ELECTRIC COMPANY 2301 M ARKET STREET P.O. BOX 8699 1881 -1981 PHILADELPHIA. PA.19101 SHIELDS L. D ALTROFF ELECTnec pm o c som January 25, 1984 Docket Nos. 50-277 50-278 Mr. John F. Stolz, Chief Operating Reactors Branch #4 Divisicn of Licensing U.S. Nuclear Regulatory Commission Washington, D.C.
SUBJECT :
Containment Purge and Venting (NUREG, 0737, Item II.E.4.2), Peach Bottom Atomic Power Station Units 2 and 3
Dear Mr. Stolz:
By letter dated December 12, 1983 (J. F. Stolz to E. G.
Bauer, Jr., PECo), you transmitted the staff's evaluation of the containment vent and purge issue for Peach Bottom Atomic Power S tati on.
The letter requested several commitments for plant modifications and revisicns to the Technical Specifications.
A response to these requests is provided as follows:
i l
1.
NRC Positicn i
Philadelphia Electric Company's letter of November 8,
- 1982, I
identified the need to modify the debris screens on Unit 2 during the next refueling outage beginning March 1984.
The l
staff concludes that this action will ensure that isolation valve closure at Peach Bottom will not be prevented by debris.
1 8401270474 840125 PDR ADOCK 05000277 P
PDR 40
...~~
. Mr.. John F. 'Stolz.
'Paga.2 iPECo Response The modification identified in the November 8, 1982, letter was: completed during the recent pipe inspection and repair outage on Unit 2.
Consequently, this item has now been clos ed.
1!.-
NRC. Position
~
The. Standby Gas Treatment-System (SGTS) and associated duct work should be modified to withstand the pressure
, differential that develops across the filters.during the postulated' design basis accident with the 18-inch vent valves fully opened; or as an alternative to modifying the SGTS, additional purging restrictions should be incorporated into the Technical Specifications.
The alternate solution is based on -reducing the plant risk contribution due to SGTS
' failure by placing' restrictions on purge and vent operations through the 18-inch purge lines.
These restrictions are as follows:
Limit the use of the 18-inch purging system to 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> (a ) _ per year in the ? power, startup, and hot shutdown modes.
(b)
Whenever the purge system is used during the power, startup, and hot shutdown modes, only one of the two SGTS trains will be used.
(c) ' Both SGTS trains are determined to be operable whenever the purge system is in use.
PECo Response We have elected to implement the alternative solution involving additional Technical Specification restrictions.
A formal License Amendment Request will be submitted by April l
'30, 1984, that -proposes a modified version of restriction l
(a ),.(b), and (c).
By correspondence dated December 11, 1979, we committed to,L and since implemented, a 90-hour per i
L year limit on containment purging for each unit.
Additionally, as noted in your letter, a License Amendment Request to incorporate this limit into the Technical Specifications was submitted on July 31, 1979.
We plan to j.
propose a minor variation of the 90-hour restriction that L
would. (1) permit a total purging time of 180 hours0.00208 days <br />0.05 hours <br />2.97619e-4 weeks <br />6.849e-5 months <br /> per year for the two-unit f acility, and (2) permit unused time
M r. John F. Stolz Page 3 (difference between 180 hours0.00208 days <br />0.05 hours <br />2.97619e-4 weeks <br />6.849e-5 months <br /> and actual annual purging time) to be carried over to subsequent years, provided the total purging time for the f acility in any one year does not exceed 270 hours0.00313 days <br />0.075 hours <br />4.464286e-4 weeks <br />1.02735e-4 months <br />.
The NRC's 90-hour per unit purging restriction is equivalent to 1% of a calendar year.
A plant limit of 180 hours0.00208 days <br />0.05 hours <br />2.97619e-4 weeks <br />6.849e-5 months <br /> per year would maintain an average annual purging time of 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per unit.
The carry-over provision would permit the utilization of unused purging time during subsequent years without exceeding an average annual purging time of 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per unit.
Therefore, the long term risk associated with purging would not be increased.
The 270-hour limit utilizing carry-over time is equivalent to 1 1/2% of the calendar year per unit.
Additionally, as proposed in the July 31, 1979 Amendment Application, the limit on purging time should apply only to those periods when a LOCA is possible (i.e., when the reactor pressure is greater than 105 psig with the reactor critical and the mode switch in the "Startup" or "Run" position ).
The purging limitations we are currently considering for the license amendment application are stated below.
A detailed justification for these variations will be provided with the
=
applicati on.
When the reactor pressure is greater than 105 psig with the reactor critical and the reactor mode switch in the "Startup" or "Run" mode, primary containment purging using the 18-inch valves shall be subject to the following restrictions:
a)
The time a flow path exists shall be limited to a total of 180 hours0.00208 days <br />0.05 hours <br />2.97619e-4 weeks <br />6.849e-5 months <br /> per year for both units except as follows.
~
Unused time (diff erence between 180 hours0.00208 days <br />0.05 hours <br />2.97619e-4 weeks <br />6.849e-5 months <br /> and actual annual purging time) may be carried over to subsequent years, provided the total purging time for both units in any one year does not exceed 270 hours0.00313 days <br />0.075 hours <br />4.464286e-4 weeks <br />1.02735e-4 months <br />.
b)
Only one of the two SGTS trains shall be used for containment purging at any one time.
c)
Both SGTS trains shall be operable when purging containment under the above conditions.
3.
NRC Position The staf f provided Sample Technical Specifications (STS) as part of its July 7,1982, transmittal, and requested that we review our existing Technical Specifications (TS) against the aample.
Philadelphia Electric stated in their August 26, L
g, y
,u
,a
.a.
iw
Mr. ' John' F. S tolz Page 4 1982, letter. that the _ current Peach Bottom Technical Specifications adequately addresses the items in the STS.
It-is the staff's position that.the current TS do not address all the ' items -in the.STS, particularly -the commitments in
- Sections 3.6.1.7 and 3.6.3.
1 Provide an application for a change to the TS addressing each item in the STS and/or a justification why each is inappropriate.
PEco Response.
The Peach Bottom Technical Specifications currently meet the intent of the Sample Technical Specifications.
The deviations are minor, or involve specifications describing maintenance practices that normally are not considered appropriate for incorporation into the Technical Speci fi cati ons.
However, at your request, we will submit an application for a change to the Technical Specifications addressing each item in the STS and/or a justification why each is inappropriate.
These changes will be included in the
=1 April.30, 1984, application described in our response to item
'2.
4.
NRC Position
-NUREG-0737, Item II.E.4.2(7), states that containment purge and vent isolation valves must close on high radiation signals.
The BWR Owners' Group performed an assessment to determine the benefits of providing this f eature.
The staff i
concluded that the Owners' Group's rational for not installing a high radiation isolation signal on purge and vent isolation valves in not acceptable.
We request that the licensee 're-evaluate its position and advise us of your schedule' for implementation.
-PECo Response We have completed our evaluation of this issue and prcpose that the containment vent and purge lines greater than 3 inches in' diameter be isolated on a high radiation signal F
which meets the criteria contained in enclosures 4 and 5 of your December 12, 1983, letter.
At this time, we plan to utilize one of the non-saf ety grade off-gas stack radiation detectors that monitor various plant discharges, including
-those f rom ~ the containment vent and purge lines, to initiate the isolaton trip.
This installation will be completed by the end of the second refueling outage on Unit 2 (currently 4
t
.~
Mr. - John F. Stolz Page 5 schsduled for Spring 1986) and the next refueling outage on Unit'3 (currently scheduled for Spring 1985).
If you have any questions or require further information on.this matter, please do not hesitate to contact us.
Very truly yours,
[,ght'
/
cc:
A. R. Blough, Site Inspector