ML20244D812
| ML20244D812 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 06/09/1989 |
| From: | Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8906190270 | |
| Download: ML20244D812 (3) | |
Text
]
e
. A n
I PHILADELPHIA ELECTRIC' COMPANY.
23ol MARKET STREET 1
P.O. BOX 8699 ~
PHILADELPHIA, PA.- 191o1 i
I 12151841-4000 l
. June 9, 1989 Docket Nos. 50-352 License No. NPF-39 U.S. Nuclear Regulatory Commission Attn: Document Control Desk' Washington, DC 20555
SUBJECT:
Limerick Generating Station, Unit 1 Temporary Waiver of Compliance
Dear Sir:
I Philadelphia Electric Company (PECo) request's-a temporary waiver of compliance for Limerick _ Generating Station,-Unit 1, to, allow time for processing of an emergency Technical Specification change request.
Section 4.1.3.5.b.2 of the Limerick Generating Station Technical" Specifications' states that once per 18 months the accumulator check valves will be timed for ty? to ten minutes to determinerif they hold accumulator /pressureLwith the' control rod drive pumpsLoff.
This test has be'en performed lsix times in the'past with data being recorded as required.
The data has not been used to i
make any operability judgements in:the past.
The last performance l
on May-9, 1989 was' driven by the reporting of. leaking accumulator
]
check valves at Dresden Unit 2 in INPO SEN 59.
During'this' test.on
.)
May 9, 1989, 17 accumulator check valves did not maintain-pressure above the alarm setpoint.
The results of this test haditwo l
accumulators depressurize during.the first 2 minutes, seven.from 2 minutes to 5 minutes, and nine from 5 minutes to 10 minutes. -Unit 1 1
was started up on May 15, 1989, and is~ currently operating at.80%
power.
L i
In this condition the accumulator. check. valves could allow'
- i the accumulator pressure to bleed down.with the control rod drive pumps tripped.
In that case the accumulators would not be able to assist in the scramming of rods.
However, reactor pressure above j
600 psig is sufficient to-scram the-rods without the assistance of l
the accumulator.
Therefore, the depressurization of the L
accumulators through_the accumulatorLcheck valves is not:significant j
in_the current operating condition.
1 f
w/
8906190270 890609 PDR ADOCK 05000352 i
p PDC
__m___.__m-_=----h--
I 1
- Documtnt Control Desk Junn 9, 1989 l
.Page 2 s
The data from the May 9, 1989 test will be' evaluated with
~
the NSSS supplier to provide input for further evaluation of the check valves' capabilities.
)
As part of permanent corrective actions, the surveillance-test, ST-3-047-790, which satisfies Tech.. Spec. 4.1.3.5.b.2, Control Rod Drive Accumulators, has been. revised to include an evaluation of.
the test results by the Reactor Engineer.
This evaluation will address the operability of the accumulators.
In the interim, Hydraulic Control Units which fail the 10 minute criteria will have-J correction maintenance and/or retesting performed.
The revision to ST-3-047-790 includes the initiation of maintenance request forms on j
the hydraulic control units which alarm on low pressure.during the
/
test.
The revision also provides for the performance of the ST at the beginning of a refueling outage and the scheduling of maintenance during the current outage for those accumulators'which alarm on low pressure during the test.
The test will be. performed post-maintenance, and during.each cold shutdown for ISI.
To complete the corrective action, PECo will request emergency l
processing of a Technical Specification change request to revise the-j requirements for accumulator operability to be applicable above 600 psi only.
This change request will be submitted on or before June l
12, 1989.
A justification for this temporary waiver of compliance j
follows.
The scram accumulator, as described in FSAR Section.
{
4.6.1.2.4.3.9, stores sufficient energy to fully insert a control rod at lower vessel pressures, where lower pressures are defined as less than 600 psig.
Above'this value, the vessel pressure is great i
enough to insert the control rod without the assistance of the scram' l
At the current plant' conditions reactor pressure is
)
sufficient to scram the control rods without~ assistance from'the-accumulator.
IN OPCON 1 reactor pressure is sufficient to scram rods without the accumulator.
A review of Technical Specifications shows that when reactor pressure is less than 756 psig in OPCON.1 the-MSIVs will isolate.
This isolation will cause a scram in OPCON 1 on i
MSIV closure.
Any event, therefore, which would; slowly depressurize-I the reactor, would cause a scram on MSIV isolation prior to pressure i
dropping below 600 psig.
A review of transients in Chapter 15 of
.i the FSAR shows that for depressurization events, that would reduce reactor pressure below 600 psig, a scram occurs within 5 seconds of I
event initiation.
This scram at 5 seconds is fast enough to ensure the rods would scram on accumulator pressure event if the control rod drive pumps tripped and accumulators began to depressurize.
The.
test results indicate that the check valves hold for at least 30 seconds before alarming, which allows sufficient time for the scram l-to occur.
Plant Off-Normal procedure ON-107, Control Rod Drive (CRD)-
System Problems, directs the RO to scram the unit with two or more
'pocum:nt' Control Desk ^
Juna.9,J1989;
.Page 3
-accumulator annunciators and the CRD' pumps off.
This' procedure'is taught in LOR training via lesson planLLOR 88-05-A..
Also,-a-
~
simulator scenario, CRD Pump Trip STS-38,cis used which.provides. thel operator with the situation.where the control. rod drive pumps trip and accumulator alarms begin to annunciate due to loss of-pressure.
In this scenario the operatornis taught to scram the unit ~when'the second accumulator alarm comes up with no control rod drive pump:
running.
Based on the above-discussion, theLtemporary waiver of compliance is justified..
- Very truly yours,.
)$ b.
phi.
G. A. Hunge, Jr.
Director Licensing:.Section Nuclear Support. Division cc:
W. T. Russell, Administrator,. Region I, USNRC T. J.-Kenny, USNRC Senior Resident Inspector i
1 i