ML20086H628
| ML20086H628 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 11/27/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20086H624 | List: |
| References | |
| NUDOCS 9112090259 | |
| Download: ML20086H628 (9) | |
Text
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UNITED STATES l'
E NUCLE AR REGULATORY COMMISSION n
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SAFETY EVALUATION BY THE OFFICE Or NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 81 TO FACILITY OPERATING LICENSE NO. NPF-11 AND thENDMENT NO. 65 TO FACILITY OPERATING LICENSE NO. NPF-18 COMMONWEALTH EDISON COMPANY LASALLECOUNTYSTATION, UNITS 1ANDJ DOCKET NOS. 50-373 AND 50-374
1.0 BACKGROUND
Comonwealth Edison Company (Ceco) submitted by letter dated October 10, 1990, an application-to amend the Technical Specifications (TS) for the LaSalle County (Station, Units 1 and 2, to modify their existing High Pressure Core Spray HPCS) and Reactor Core Isolation Cooling (RCIC) systems due to two underground piping failures they had experienced in 1985. The initial submittal was reviewed by the staff and in response to the deficiencies noted by the NRC staff and the licensee's own technical staff, the licensee submitted an amended application by letter dated October 16, 1991. This letter provided additional clarifying information that did not change the initial proposed no significant hazards consideration determination.
The normal surveillance piping for both the RCIC and HPCS systems tales suction from the Condensate Storage Tank (CST) and discharge, back to the CST via a full flow test return line. Both the suction and return lines pass underground.
Both systems also have the ability to take suction from the suppression pool.
In addition, the_HPCS system has a full flow test return line to the suppression pool that can be used as an alternate means of testing the HPCS system. The RCIC system is not equipped with this feature. The suction aad return piping to the suppression. pool does not run below ground on either system.
During a preseevice inspection and hyrdrostatic test, a failure was discovered on an above ground elbow joint weld located imediately adjacent to the CST on the Unit 2 RCIC system. This failure was attributed to intergranular corrosion. The licensee was concerned about the integrity of the underground piping and decided te N place the underground portions of the system with a heavier schedule pir-we.pped in a material designed to reduce the potential J
for intergranular co. w, ion at the weld joints.
The second failure was discovered in May 1985 and involved the HPCS piping.
The-failure was detected when water seepage was observed at ground level above the HPCS full flow return line to the CST. This failure was attributed 9 1 9, 0 3 h h r P
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i
. to a form of microbiological corrosion which primarily affects the weld material. The problem was temporarily corrected by isolating the failed li;ie and aligning the HPCS system to the suppression pool.
Due to the failure of the underground HPCS piping, the licensee performed an evaluation to determine the effect on plant operations of a similar failure on the RCIC piping, it was determined that there would be no way to perform the quarterly surveillance test without directly injecting water into the reactor vessel.
Based on the results of this evaluation, the licensee decided on the following corrective actions for both systems:
1.
Periodic tests are being performed to monitor the integrity of the underground RCIC piping.
2.
Improvements to the current cathodic protection system were made and plans to install additional deep anode systems that will help to minimize corrosion damage to the underground piping over the lifetime of the plant have been initiated.
3.
The licensee decided to permanently isolate and abandon in place the HPCS system suction and full flow test return lines to the CST (see figure 1).
4.
A modification which will give full flow test capability to the suppression pool for the RCIC system will be installed during each unit's refueling outage (see Figure 2). This modification would be used should a future failure occur to the underground RCIC piping.
As a result of the HPCS system modifications and planned modifications to the RCIC systemt the licensee deterM ned that changes to the TS were required to achieve consistency between the system design modifical. ions and the TS requirements. These changes are contained in the licensee's October 10, 1990, and October 16, 1991 submittals.
2.0 DlaCUSSION 2.1 Proposed HPCS TS Changes Since the discovery of leakage from the HPCS system suction and full flow test lines to the CST, these lines have been isolated and administrative 1y controlled. The licensee's HPCS system modifications will permanently isolate the suction and test lines. As a result, the current TS requirements for the HPCS system suction flowpath transfer will no longer be required. The licensee proposed the following changes to the TS in their October 10, 1990, submittal.
Remove instrumentation requirements for the CST low level trip aM suppression pool high water level trip from the ESF Division 3 requirements in Tables 3.3.3-1 (including ACTION 36), 3.3.3-2 and 4.3.3.1-1 Since, the UPCS system suction is permanently lined up La the suppression pool, neither of these trips are required for safe plant operation.
'e
.* Remove Surveillance Requirement 4.5.1.c.3 which requires serification of the HPCS system suction flow path automatic transfer f w the CST to the suppression pool. Since, the HPCS system suction ^ '. w is permanently lined up to the suppression pool there is no onger any need to test the automatic transfer capability.
Remove references to the CST from the HPCS system flow path requirements in TS Limiting Condition For Operation (LCO) 3.5.2.e.
The CST flow path is not required for plant safety but was allowed to be used during shutdown as an alternate water source when the suppression pool sas drained. This option is no longer available and will no longer be used.
Remove Surveillance Requirement 4.5.2.2 for verification of HPCS system operability by verifying the acceptability of the CST water level.
With the LCO deleted this surveillance would no 1cnger be required.
Remove the references to the CST from the suppression pool volume requirements in TS LCO 3.5.3.b.
Since the CST is no lunger available via the HPCS system flow path, exceptions to the suppression pool level requirements that rely on the additional water volume contained in the C3T can no longer be allowed.
Surveillance Requirement 4.5.3.2 must be amended to remove Paragraph "a" which refers back to the conditions being deleted from TS 3.5.3.b.
Since the remainder of Surveillance Requirement 4.5.3.2 is applicable only in Operational Condition 5, the reference to Operational Condition 4 is being remosed.
Remove the reference to the CST from the bases of TS 3/4.5.1 and 3/4.5.2.
Remove the reference to the HPCS suction valve transfer from Bases Figure B 3/4.6.2-1.
Evaluation The HPCS system is designed to be normally aligned to take suction from the The suction CST, which provides an additional source of primary system water.
valves to the suppression pool would normal' be closed in this configuration.
'The UFSAR states that credit for this water is not taken in the accident analysis; therefore, the CST is only expected to function during normal plant conditions and performs no safety function.
Since no credit for the water in the CST is taken in the LaSalle accident analysis, the staff has concluded that removal of the associated requirements in the TS is acceptable. On this basis the staff has. reviewed the proposed TS changes for removal of CST requirements described above and finds them acceptable.
The licensee's addendum of October 16, 19S1, requested that Table 3.6.3.3-1 revised to change the thermal overload bypass device on motor be additionally (MOV) 1(2)E22-F015 from accident to continuous operating operated valve conditions. This valve is located on the HPCS suction line from the suppression pool.
In the new configuration, this valve will normally be open. Closure of this valve would occur only in :he event of a suction line break on the l
- y e.
L
. -HPCS system suction line, anc for maintenance. The licensee:has stated that since this valve is not uniplated, thermal overload protection durinq normal operations is not needed.
However, a bypass of the thermal overload protection to prevent this circuit from inhibiting the valve from performing its safety function is required.
Evaluation Requiatory Guide 1.106 (RG 1.106) provides the staff position on thermal overload protection for electric motors on MOVs.
In order to ensure that safety-related MOVs which are equipped with thermal overload protective devices will perform their safety function, two types of bypasses may be used. The thermal overload protection can either be continuously bypassed or bypassed under accident conditions only.
RG 1.106 states that-provided that the completion of the safety function is not jeopardized or that other
-safety-systems are not degraded, then the thermal overload protection devices should be continuously bypassed and temporarily placed in force only when the valve motors'are undergoing periodic or maintenance testing. Accident condition bypasses'should be used where the thermal overload protection is required for valves-that are requiarly manipulated during normal plant operations.
Since this valve will not be manipulated durinq normal operations,_
an accident condition bypass is not required for the HPCS suction valve. On this basis, the staff finds the use of a continuous bypass acceptable.
2.2 Proposed RCIC TS Changes The licensee's-planned modification to install an RCIC system full flow test line to the suppression chamber is being performed to minimize the impact TS 3.7.3 on plant operations of any future RCIC underground pipinq failure.
- requires the RCIC system to be operable _and to have an operable flow path from the suppression pool to the reactor vessel.. A failure of-the RCIC underground lin.es to' the CST would-not necessarily render the system inoperable immediately because the specified flow path from the suppression pool to the reactor.would be unaffected. However, if a failure involved the full flow-test line to the CST, performance of the quarterly pump performance: surveillance wouldbedifficult(SurveillanceHequirement4.7.3.b). Under these conditions the.only mears of performing this test would.be by actual injection to the -
reactor vessel.
Since an RCIC system injection causes a' trip'of the main turt Me and the feedwater pump turbines, reactor power would have to be reduced and the-turbines would have to.be shut down prior tn performing the surveillance.
This would be a costly option since it would require a power reduction-outage every three months until repairs or modifications-to;the underground piping
-could be complettd. The licensee's preferred and planned option (refer to Fiqure 2) is to install (1) an additional full fi x test line to the suppression-pool for tne RCIC system, and (2) to in tall a flanged joint downstream of the 1(2)E51-F059 valve where a blind flange can be installed. This option will-increase the RCIC system flexibility, such that an underground piping -
failure would have a minimal impact on plant operation and safety. This e-
.* -- modification is scheduled to be installed during the next refueling outage for.each unit. -(Unit 1, October 1992, Unit 2 January 1992.)
As a-result of these planned modifications, the licensee has proposed TS changes which add the RCIC system full flow test valves 1(2)E51-F059,
- 1(2)E51-F022,1(2)E51-F362,and1(2)E51-F363 totable 3.6.3-1," Primary Containment.lsolation Valves." The licensee proposed the following changes to the TS in their October 10, 1990, submittal to be implemented prior to startup from the next refueling outage for each unit.
Add the fellowing valves and associated footnotes to the Primary Containment Isolation Valves list, Table 3.6.3-1:
'l E51-F05^ footnote m 1
E51-F022 footnotes j and m 1
E51-F362 footnote n 1
,E51-F363 footnote n Relocate existing footnotes from Table 3.6.3-1 to new page 3/4 6-34a for Unit 1 and 3/4 6-37a for Unit 2.
Add new footnotes m and n as follows:
If valves 1(2)E51-F362 and 1(2)E51-F3E3 are locked closed and m.
acceptably leak rate tested, then valves 1(2)E51-F059 and 1(2)E51-F022 are not corsidered to be primary containment isolation valves and are not required to be_ leak rate tested..
If valve 1(2)E51-F059 is deactivated and locked closed with n.
the line blind flanged downstream of the valve and acceptably leakage rate tested, valves 1(2)E51-F362 and 1(2)E51 F363 are not considered primary-containment isolation valves and are not'. subject to leakage rate testing requirements.--
.Removemotoroperatedvalves1(2)E22-F001,1(2)E22-F010,and1(2)E22-F011 from Table 3.8.3.3-1 since these valves are to be permanently out-of-service closed.
Evaluation As a result of these modifications to the RCIC system, the licensee proposed L
.that valves E51-F022, E51-F059, E51-F362, and E51-F363 be added to Table 3.6.3-1,
" Primary Containment Isolation Valves." Since this will ensure that primary containment -integrity is maintained by instituting a 3propriate-controis for operation and testing of these= valves as required,- tie staf f finds this acceptable.
'The licensee also proposed to add footnotes m and n to TS 3.6.3-1.
If the system is lined up to CST, valves E51-F3f2 and E51-F363 will be considered In
- to be primary containment isolation valves and will be locked closed.
that case, footnote m will be applicable which states, "if valves E51-F362 and 1
s-
.* E51-F363 are locked closed and acceptably leak rate tested, then valves E51-F059 and E51-F022 are not considered to be primary containment isolation valves and are not required to be leak rate tested." The staff finds the above footnote m acceptable as double locked closed manueI isolation velves meet the requirements of General Design Criteria (GDC) 56, for primary containment isolation.
The licensee proposed that if the system were lined up to the suppression pool for test purposes, footnote n would be applicable.
Footnote n as proposed stated "if valve E51-F059 is deactivated and locked closed with the line blind flanged downstream of the valve and acceptably leak rate tested, valves E51-F362 and E51-F363 are not considered primary containment isolation valves and are not subjected to leakage rate testing requirements." The licensee indicatei that containment isolation would be provided by motor-operated isolati'n valve E51.F022 and the RCIC pipin; boundary. The staff ccnsidered that a single isolation valve was not acceptable for a new line and that if the 3ystem were lined up to the suppression pool, the licensee should designate one of the two manual isolation valves E51-F362 o* E51-F363 as an isolation valve and keep it locked closed except during surveillance testing, when it would be under administrative controls.
In e conference call with tne staff on July 25, 1991, the licentee agreed to the above requirem' t and in letter dated October 16, 1991, revised the wording in footncte n c-sble 3.6.3-1 to read as follows:
Either the 1(2)E51-F362 or 1(2)E51-F363 valve may be open when the n.
RCIC system is in the standby mode of operation, and both valves may be open during operation of the RCIC system in the full flow test mode, providing that:
- 1) valve 1(2)E51-F022 is acceptably leak rate tested, and 2) valve 1(2)E51-F059 is deactivated, locked closed and acceptably leak rate tested, and 3) the spectacle fienge, installed immediately downstream of the 1(2)E51 '059 va tve, is closed and acceptably leak rate tested.
The staff has concluded that the revised footnote n meets the containment isoiation requirements of ' 3C 56 and is, therefore, ac eptable.
2.3 Proposed Adminstrative TS Chances The licensee's October 10, 1990, and October 16, 1991, submittals also proposed several administrative TS changes and correction of typographical errors. The most significant of these changes included:
Deletion of Footnote "***" located in Tables 4.3.3.1-1 and 3.6.3-1 of the Unit 1 TS. These footnotes allowed several 18-month interval surveillancr. requirements to be waived during the fitst cycle of operation.
o 8,
Removal of the reference to footnote "j" from valve 1(2)E51-F022 in-Table 3.6.3-1 which was inadvertently included in the October 10, 1990 submittal.
The inadvertent omission of the deletion of footnote (d) from page 3/4 3-26 for Unit 1.
-The staff has reviewed these changes and determined that they are administrative in nature and have no impact on pisnt safety. On this basis, the staff finds them acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Illinois State official c
was notified of the proposed issusnce of the amendments. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendn.ents charge a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements. The NRC staff has dE termined that the amendments involve no significant increase in the amounts, and no significant thange in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (d5 FR 47569). Accordingly, the amendments meet the eligibility-criteria for categorical exclusion set forthin10CFR51.22(c)(9). Other changes are administrative and are eligible for categorical enclosure under 10 CFR 51.22(c)(10). Pursuant to 10 CFR 51.22(b), no enviror. mental impact statement or environments 1 assessment need be prepared in connection with the issuance of the amendments.
j
5.0 CONCLUSION
The Commir.sion has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by op stion in the proposed manner, (2) such activitiec will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common r
defense and security or to the health and safety of tha public.
Attachment:
Fiqure 1, HPCS System Modifications figure 2, RCIC System Modifications Principal Contributor:
B. Siegel/R. Elliott/R. Goel/M. Razzaque Date: November 27, 1991 j
1 i
.t FfGURE 1 o
r l?CS System Current Alignment
'N M
1 HPCS Pump h
(2)E22-F004
~~
/
y y
4 l
Reactor 1(2)E22-f023 g_I I 2-Vessel F005 kM 1(2)E22-F012
.. ~3
\\ /
Before the IIPCS line break, these g_
j valves were
/
normally closed, but opened for 1(2)E22-F010 Condensate full flow test.
y Storage Now they are Tank out-of-service Sup ression closed.
1(2)E22-F011 This valve This valve was normally closed.
was nor-Now it is normally opened.
mally open.
NN
___N1(2)E22-F016 1(2)E22-F002 b/
"!- 0I-f Now, it is servlCe X
oN
!/>
kN closed.
1(2)E22-F015 1(2)E22-F001
. - aj
-,y Figure 2-RCIC Full Flow Test Return To Suppression Pool 2CIC Pump i
X
)
1(2)E51-F013 1(2)E51-F022 Vessel Addition t(s)sst-rs44 3
1(2)E51-F363 1(2)E51-F362 1(ejast-rses X
t(r)sst-rsos 1(a)s51-r30s K
t1 (2)E51-F059 Condensate N<
fIPCS Storage V
3 Tank Sup r on Test IJne Prw heem l
1(2)E21-F012
( r rg Addition N
1(2)E51-F030 1(2)E51-W11 X
N
/
X 1(2)E51-F031 1(2)E51-F010
,