ML20206L830
| ML20206L830 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 08/08/1986 |
| From: | Tucker H DUKE POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8608200310 | |
| Download: ML20206L830 (15) | |
Text
V DM b DUKE POWER GOMPANY P.O. Box 33180 hk g
CHAHLOTTE, N.O. 28242,,
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a HAl. B. DJGKER 1
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U, TELEPHONE
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.,.x, (704)073-453:
mra. man, nom ovson August 8, 1986 J. Nelson Grace, Regional Administrator U.S. Nuclear Regulatory Commission Regt>n II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
Subject:
McGuire Nuclear Station IE Inspection Report 50-369/85-38 and 50-370/85-39
Dear Dr. Grace:
By letter dated June 27, 1986, NRd/RII forwarded subject inspection report which provides the results of inspection conducted relative to the Nuclear Service Water System Operability at McGuire.
As the apparent violations are under consideration for possible enforcement action, no response to the report was requested by the NRC. However, Duke believes that a submittal is in order because the report contains some inaccurate statements which can be misinterpreted and some errors of omission in that relevant actions taken by Duke are not described. Detailed comments are provided in the attached.
Duke requests that the information contained herein be considered by the NRC prior to issuance of any Notice of Violation.
Very truly yours, d
?
Hal B. Tucker RIE/84/jgm Attachments D
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Dr. J. Nelson Grace I
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', August 8, 1986 Page 2 xc:
W.T. Orders NRC Resident Inspector McGuire Nuclear Station Darl Hood, Project Manager Offfee of Nuclear Reactor Regulation L.S.,!uelear Regulatory Connaission Washi.ngton, D.C.
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DUKE POWER COMPANY McGUIRE NUCLEAR STATION CO)MENTS CONCERNING IE INSPECTION REPORT 50-369/85-38 AND 50-370/85-39 Introduction The comments on the report are presented in order consistent with the report itself.
Page 2 Section 6, First Paragraph: This paragraph fails to provide some details of actions taken by Duke.
On October 4,19851A RN pump failed to meet its quarterly ASME Section II IWP l
acceptance criteria. The pump was declared inoperable and the unit entered into a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> LCO. In accordance with IWP-3230 (b) 1A RN pump impeller was replaced during this 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> LCO. Visual inspection of the pump impeller did not reveal the magnitude of wear that would be expected with the step change in the pump's performance. The pump was retested in accordance with IWP-3111 to reestablish inservice reference values; however, the pump did not meet its FSAR head curve.
After considerable testing and troubleshooting it was decided that the most likely cause of the pumps degraded performance was the flow instrumentation. A 10CFR 50.59 evaluation was then performed to cross-tie 1A and 2A RN Trains together as a temporary measure. The crose connection of the two RN Trains was in accordance with IWP-3230 (c) which states: " Correction shall be either replacement or repair per IWP-3111, or shall be an analysis to demonstrate that the condition does not impair pump operability and that the pung will still fulfill its function."
Page 3 First Paragraph, 3rd sentence implies licensee merely " stated" the flow indication was erroneous. In fact, the sentence should read: " Licensee subsequently proved through extensive testing and modifications to the system that the flow indication was erroneous and the pump was not actually degraded".
During one of the numerous telephone conversations, a member of the NRC staff indicated that he was concerned about the Containment Spray heat exchanger fouling based on the high differential pressure and the visual inspection performed at Catawba Nuclear Station. It is misleading to say that the NRC became concerned just because fouling had occurred at the pump discharge.
Item a. let bullet - The tests referenced were used to gather data and were informational. A procedure used to gather data does not test a component / system and therefore no acceptance criteria is needed/ required. The data that is gathered in then used to trend parameters or is used by the engineering staff for evaluation. The procedures satisfactorily gathered data which was the purpose of the tests.
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Item a. 2nd bullet - Flow was measured indirectly for the control room air condi-tioner heat exchangers for Unit 1 but was not measured for Unit 2.
The inlet piping and the complete discharge path is common to both Unit I and 2.
Therefore the only Unit 2 specific flow path that would not have been tested by the Unit 1 pre-op test was the flow path from the Unit 2 essential header up to and including the Unit 2 inlet isolation valve to these heat exchangers.
Item a. 3rd bullet - Even tt.ough the test results were recorded in units of Delta P, the acceptance criteria was met as documented on the tests.
The Delta P instruments used were more accurate than the process instruments for determining flow.
Item a. 4th bullet - This is typical of the entire nuclear industry and is not a McGuire concern only. There is no regulatory requirement for testing of these heat exchangers. There are no endorsed Nuclear Standards or Regulatory Guides that require heat transfer characteristics to be performed. The system was not designed to perform heat transfer testing at design conditions.
Duke Power developed test techniques to ascertain the heat transfer characteristics of the Containment Spray heat exchangers which otherwise has no heat load. Additionally, Duke Power had recognized the need for this type of monitoring to be performed and was in the process of developing guidelines and acceptance criteria in an orderly manner.
Item a. 5th bullet - The RN system was tested to the FSAR abstract which was accepted by the NRC prior to licensing.
Item c - The " engineering documents" were recommendations and not requirements and were treated as such.
Page 4 Item d - Contrary to the leadoff sentence of this section, these items cannot be considered " major findings".
See attached graph. The NS heat exchanger differential pressure was being moni-tored for asiatic clams. A continuous increase in heat exchanger differential pressure would be indicative asiatic clam growth. The differential pressure across this heat exchanger spiked during lake turnover periods and then returned to its original level. This increase in differential pressure did not indicate a I
. clear trend until the fall of 1985 when the second spike occurred.
Also, the report fails to note that the September 1984 inspection of the Unit I component cooling water heat exchanger was in response to the previously observed fouling of the non-safety related containment ventilation heat exchanger.
Item e - This paragraph incorrectly quotes the Technical Specifications action statement " required the operating unit to be brought to the hot standby mode within six hours".
On October 4, we correctly applied T.S. 3.7.4 by declaring 1A RN System inoperable. This then required us to restore operability within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in hot standby within six hours after that point. Another technical l
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i misstatement was that the A & B Trains of Unit I were cross connected. The station cross connected Unit 1 A Train with the Unit 2 A Train of RN.
l The 1A RN Pump was declared inoperable at 2030 on October 4, 1985 and the action statement of LOO 3.7.4 was entered.
We contend that the 50.59 safety evaluation associated with the cross connection of Unit 1 RN Train A with Unit 2 RN Train A was properly performed and did not involve an unreviewed safety question. This cross connection was essentially the same as Catawba's design.
10 CFR 50.59 allows a licensee to make changes without prior NRC approval if an unreviewed safety question is not involved and the margin of safety as defined in the basis for any technical specification is not reduced. Neither of these conditions were involved in the cross connection.
Additional discussion is provided in comments in section labeled "Page 10".
Item f - The last sentence states "The licensee apparently assumed the system to be operable between December 17 and January 14".
The phrase "apparently assumed" is an opinion. We did not make an assumption on the operability of the RN System.
The test run on December 17 was intended to be an "information only" test to determine the best method to conduct a flow balance test. After completion of this test, engineering staff at the station contacted Design Engineering, and G.O.
Licensing with the question of the low flows on the heat exchangers. At that time, the consensus determination was that the various components were in a j
degraded mode, but were not inoperable. One heat exchanger was inspected and j
cleaned in response to the test data; however, an earlier work request was already in process to inspect the same component. Design operability statements confirmed the operability of the components that indicated low flow in the December 17, 1985 test.
Fourth Paragraph - The phrase "although it appears" is an opinion.
4 Heat exchangers with an active heat load were cleaned since they were the first to have recognized symptoms of fouling.
In the developmental stages of Duke Power's raw water heat exchanger program, it was believed that the fouling was the result of some microbiological organism acting as the " glue" to bind the silt / mud to the heat exchanger tubes.
It was believed that heat load enhanced the growth of these j
organisms and that fouling was not occurring to the same rate or degree in the dormant safety equipment.
I This paragraph gives short shrift to the actions taken by Duke personnel.
Fifth Pararraph - The report states that "this mode of operation complies with regulatory requirements" yet offers the opinion that this does not appear to re-present the most conservative safety philosophy. Duke believes that violations i
should be based on factual considerations.
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Page 5, Section 7 l
Second Paragraph - This paragraph gives sn==ary treatment of Duke actions j
regarding use of "not applicable" for safety evaluations.
As, explained during the
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January 1986 inspection, it was determined that 10CFR50.59 applies only to a
" holder of a license" which did not apply to McGuire procedures used prior to Fuel Load. The APM section referred to is applicable to all procedures used at the station. Rather than simply writing a memorandum, an exemption to the APM requirement was prepared and signed by the Vice President, Steam Production 3
j Department and the Manager of Quality Assurance.
I Fourth Paragraph - It was recognized at the time there were problems in measuring flow to the Control Room air conditioner; however, it has been shown since that time (via ultrasonic flow measurement and installation of new and relocated flow orifices) the flows were adequate. The NRC statements are incomplete in that the i
above actions by Duke are not reflected.
(See response to Item a - first bullet.)
4 Last Paragraph - The flows have been tested and proved adequate by better flow I
measurement techniques (see response to fourth paragraph above).
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1 Page 6 First Paragraph - Due to inoperable process flow instrumentation, it was necessary 4
to use test differential pressure instruments in several cases during the RN flow j
balance. The flows required were never explicitly listed in the acceptance i
criteria; instead, acceptance criteria 11.1 states: Design flows can be ea-l tablished to each component for all modes of operation as described in this 4
procedure.
4 i'
In each enclosure used for the flow balance, there is a column containing the l
acceptable FSAR flow in gpa for each component, next to the blank used to record
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the measured flow.
In each case where a change was made to record differential l
pressure in lieu of gpa, a change was also made to the Flow Required column to express the required FSAR flow in differential pressure. The intent was that one could, at a glance, verify whether the FSAR flow had been achieved, without requiring any conversion to be done. Although the conversion was not included in the procedure, it was a very simple and straightforward conversion using the 1
I proportionality of flow to the square root of the differential pressure.
It was not deemed necessary to directly convert to GPM in the procedure since the actual magnitude of the flow was relatively unimportant as long as the minimum FSAR flow was achieved.
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Page 8 i
First paragraph - The purpose of this test was to gather data to monitor for asiatic clams (i.e. clam /shell debris) and not to " test" the heat exchangers and
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therefore did not require acceptance criteria.
1982 (First Paragraph) - The report gives short shrift to relevant actions taken by Duke. The coolers were not " eventually" corrected as indicated in this paragraph, but rather were modified at the first refueling outage after the chemical attempt failed. This modification was an extensive rework of the RN piping around each of the four lower containment cooling heat exchangers on each unit.
1 Page 9 1984 (First paragraph) - The Performance Monitoring Program is very extensive and involves more than heat exchangers only. Much effort has been spent by Duke in attempts to explain the program to the NRC.
Again the report gives short shrift to responsible actions taken by Duke to improve the performance of plant systems and equipment. A discussion of the PMP is provided.
(Please see Attachment 1)
Fourth Paragraph - In this paragraph it is correctly stated that the calculations of a fouling factor were based on informal test data which appeared to the cogni-zant engineer as ron-representative. See additioual relevant comment in section entitled "Page 12".
i Page 10 Expanded 1st and 2nd paragraph - On October 4, 1985, the LA RN Pump indicated a a
failure on the quarterly pump test. The plant staff immediately began j
investigations and reconducted the test several more times with different pre-cision test instrumentation, all with the same apparent level of degradation. As part of the work, an informal pump head curve test was conducted and this also indicated degraded punip performance.
That night, the Operations Superintendent made the decision to r.eplace the pump impeller and declared the 1A RN Pump j
During the weekend of October 5-6, plant maintenance worked around the clock to replace the impeller, inspect the discharge check valve, and inspect the flow orifice. The impeller removed from the casing showed little wear, the check valve worked freely and orifice did not exhibit any erosion that would affect it's -
operation.
The plant staff, along with Design Engineering on October 7,1985 made the 10 CFR 50.59 analysis to justify cross connecting the 1A and the 2A RN Trains to continue i
operation of Unit 1.
IWP 3230(c) allows the utility to analyze operation of the pump af ter a test failure to justify return to operable conditions. Duke Power recognized that the cross connected operation was an interim solution to the apparent degradation of the 1A RN Pump, but also contended that the flow being delivered was conservative to supply safety flows. The engineering staff was fully convinced that the flow measurement was in error and the efforts had already begun to carry out the investigation.
By cross connecting the two Trains, two independent nuclear service water loops were operable. Although the 1A RN pump was suspected of being degraded, the IA and 2A pumps combined would provide the required flow for both LOC. and non-LOCA units. Design Engineering had demcnstrated this in the revised combined pump curves that were included in OP/1/A/6400/06 by Revision 50 (curve attached).
Cross connecting 1A and 2A Trains dfd not create an unreviewed safety question.
The sharing of RN Trains has been acdressed in the FSAR, Section 9.2.2.
Each RN Train has always shared common suction piping between corresponding unit Trains (i.e.: 1A-2A and IB-2B). By cross connecting the two pump discharges, the RN systems ability to perform its safety function was not impaired. The RN system in this configuration would have supplied the required flows in the event of an accident on one unit, and bring the remaining unit to an orderly shutdown and cooldown. This meets Criterion 5 of 10CFR 50 Appendix A for shared systems between units.
The redundancy required in Criterion 44 was also met.
Suitable redundancy was provided assuming a single failure.
If the failure occurred on IA or 2A Train, the shared A Train would be rendered inoperable. However, both IB and 2B would be available for accident and non-accident loads.
(Example:
1A pump failed, IB and 2B would supply required flow).
If the single failure occurred on a B Train, the shared A Train and opposite B Train would remain available.
(Example:
2B pump failed, IA-2A and IB would supply required flow, B Trains were not cross ccn-nected.)
Therefore, Duke does not believe that by cross connecting 1A and 2A was an unre-veiwed safety question, and Duke did justify the cross connection by a 50.59 analysis.
On October 10, the NRC Region II informed Duke management that they considered the cross connection alignment unjustified and required Unit IA RN Train to be de-clared inoperable. Early on October 11, a head curve test was conducted on the new 1A RN Pump utilizing two flow elements located downstream of the suspected discharge flow device.
There were several engineering justifications for use of these flow devices and at 4:15 PM on October 11, Design Engineering approved the values from the test and the 1A Pump was declared operable.
Duke Power contends that IA RN Train was operable from October 7 through October 10 even without the cross connection with Unit 2.
IWP 3220 allows up to 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> i
to evaluate test data and then an additional 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to retest if instrumentation is suspected as the potential problem. McGuire chose to investigate the pump condition instead within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> of initial test. After a thorough investigation of the pump and check valve, it became clear that the loop had an instrumentation problem.
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l 7-i If McGuire had utilized the full time allowed by ASME Section II, Unit IA RN Pump would not have been declared inoperable unit 3:00 PM on October 8, and then i
another 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of operation would have been allowed with 1 RN Train operable.
This would have allowed time for further engineering investigation of the instru-
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mentation problems, however, the plant management took the conservative direction j
by assuming that the pump was degraded.
(See response to Item e, Page 4 with respect to 50.59 evaluation)
Second bullet - This statement implies a clearly increasing D/P across the 1A NS heat exchanger. The plot of actual data has been presented earlier. The data i
shows a cyclic pattern, along with a slight positive trend.
Increasing D/P does i
not provide conclusive proof that the heat exchanger was incapable of performing j
its intended safety function. Rather, it is a cause for concerned evaluation of additional actions to be taken.
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t Page 11 First bullet - The statement "could not" is inappropriate and should be changed to i
"was not".
The operator action was to establish approximately 5000 GPM, i.e. 4600 GPM vs. exactly 5000 GPM.
l Second bullet - The report proffers the opinion that it appears doubtful that the i
required flow could have been achieved. As expressed to the NRC previously, this i
is a manually aligned system. All operators interviewed by the NRC team knew the
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required flow was 5000 gpa and would have observed for this flow when valving in j
the heat exchanger.
1 First paragraph - See response to Item a 1st bullet, Page 3 and first paragraph on j
Page 8.
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Last pragraph - These concerns were never " clearly" communicated to the station during the October 15-17, 1985 inspection or at the exit interview by the inspector. In fact, Duke responded to the NRC concerns known at the time in a l
letter dated December 2, 1985. The fact that Duke sent such a letter is not
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reflected in the report.
I Page 12 l
Second paragraph - This paragraph fails to convey the reservations of Duke personnel. The report accurately conveys these reservations on page 9.
Design Engineering personnel expressed concern to the NRC inspector over using the fouling factor derived from the KC heat exchanger; however, the NRC insisted on 4
j performing the calculation using this fouling factor since it was the only i
available number that could be used.
Page 14 Fourth paragraph - The report also makes reference to this item on page 4, item f.
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Page 16 Last paragraph - The report states that NRC Region II learned of the January 28 flow transient on March 12, 1986. When Duke Power did the flow balance on January 27 on 1A RN Train, it was noted that the pump discharge dropped into an operator alert zone when the flow rate was increased above a certain value. The plant staff recognized this as a certain sign of insufficient pump NPSH and the test made correction for the condition. On January 28, while preparing to ratest the 1A RN Train with the most conservative suction alignment, the NPSH observation was passed on to one of the NRC inspectors in the control room.
At that time, the inspector was following up on a concern about the position in which the large throttle valves were left at the conclusion of the test. The NRC inspectors had the pertinent data during the January 27-31 inspection to evaluate the adequacy of the pump NPSH. Duke was quite concerned with running into a similar problem with the required conservative alignment as stated in the FSAR.
In addition, the last sentence implies that cavitation due to insufficient NPSH is immediately catastrophic to both units.
It does not cause pump destruction such that the operators would not be able to control the system.
This is conjecture and is based on reaching the NPSH and without any operator action taken.
Page 17 Last sentence - We did not need to be advised of this requirement as the equipment was already declared inoperable and required resolution prior to declaring the equipment operable.
Tables 2,3 The footnotes inaccurately convey the LOTIC assumed thermal efficiency and the thermal performance data.
LOTIC 50%
(Ref: Duke letter dated April 25, 1986, (assumed) response to Item 5) i RN 1A 72.4%
(Ref: Duke letter dated April 25, 1986, table IB 86.6%
entitled "McGuire Nuclear Station, Containment 2A 58.5%
Spray Heat Exchanger Test Results) 2B 62.7%
(test results)
Page 18 j
Second paragraph - All operators interviewed by the KRC team knew the required flows and would have observed for the required flows when valving in the heat exchangers.
1 Page 19 Item 9 - The value used for containment sump volume was based on the Catawba volume used and since that time has been evaluated to be greater than 90,000 ft.
The report fails to note Duke's submittal dated April 25, 1986 which provides the results of a rigorous engineering calculations (see letter, response to item 5).
Again, the report gives summary treatment of substantial actions taken by Duke in this matter.
Page 22 i
Section 12 - The report expresses serious doubt, regarding past operability of the RN system. Yet, throughout the period of this inspection, Duke personnel have i
provided substantial amounts of engineering calculations. Further, Westinghouse has generated, at the request of Duke, many LOTIC computer calculttions, the results of which have been provided to the N2C promptly. All of the evaluations have been made available to the NRC for review. While Duke acknowledges that the RN system was being operated in a condition that was degraded from that which was i
specified in the original design, Duke was able to accommodate the degradation by the substantial amounts of conservatism and margin built into the design of McGuire. Yet, even so, the design and operation remained conservative and met or exceeded all applicable design basis requirements. Duke questions the conclusions of the NRC that the aggregate observations constitutes a condition that is adverse to quality.
The report identifies five concerns that constitute the " adverse to quality" conditions. Duke's response to each of these follows:
a i
1.
Significantly reduced heat transfer capability of various safety-related heat exchangers - Neither industry nor the NRC have had in place any programs that require or provide acceptable means to monitor the heat transfer capability of heat exchangers. Duke's PMP was initiated in response to concerns Duke had. This testing is still in it's development stage. However, Duke Power corrected problems on heat exchangers as identified and conducted operability j
analyses on components that appeared to be degraded.
2.
Reduced RN flows - As presented in earlier discussions, the RN pump reduced i
flow indication was attributable to instrumentation fouling. Duke has made i
plant modifications to remedy this condition.
i 3.
Improper throttle valve sett' dnile these conditions existed, they are not of such a level of import..ee as to be of concern of overall system l
operability. As detailed in discussion earlier, operators are knowledgeable i
and capable of taking corrective actions.
4.
Increased corrosion - This condition lead to items 1 and 2 above and thus j
does not constitute another independent observation.
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Lack of adequate preoperational testing. As discussed earlier, the McGuire preoperational testing was conducted in accordance with the NP.C approved FSAR abstract.
Such testing was reviewed by the NRC and approval given to str.rtup each McGuire unit.
Upon discovery of the preoperational testing inadequa-cies, retesting was conducted.
While the aggregate of observations may be cause for concern and indicate a need for action, the inspections and evaluations conducted to date have established that the overall RN system was operable.
It is noted that some individual components were inoperable and once identified by the performance surveillance testing procedures developed by Duke were promptly corrected within the allowed outage time.
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i ATTACHMENT 1 DUKE POWER COMPANY PERFORMANCE MONITORING PROGRAM BRIEF HISTORY In early spring of 1984, the vice-president of Nuclear Production Department requested the Performance Evaluation Section of NPD/ Nuclear Technical Services to develop a comprehensive Performance Monitoring Program (PMP) for the three nuclear stations. The objectives of the development were:
A.
To standardize the three stations' performance efforts.
B.
Revise / upgrade performance monitoring techniques.
C.
Increase operations / maintenance utilization of performance indices.
D.
Standardize performance staff training programs.
The development effort was conducted during the ensuing year involving station and GO persannel in a joint development effort.
It was culminated in the 1seuance of the PMP manuals to the stations in June, 1985.
The implementation effort at McGuire began July 15, 1985 with the formation of the MNS PMP Implementation Team (IT). This team consisted of the MNS PMP Coordinator, the PMP technician, and the GO PHP Support Engineer. The initial effort of the PMP IT was to develop for site management approval the MNS PMP Implementation Plan. The plan was initially issued on August 16, 1985.
As a result of the RN 1A Pump problem, the NS 1A heat exchanger DP trends, and observed VL and KC fouling levels, the priority of the RN essential heat exchangers was upgraded substantially. The efforts of the entire PHP Implementation Team was redirected to the RN system by site management effective October 24, 1985. Initial efforts focused on thermal testing and cleaning of the NS 1A heat exchanger.
These initial efforts were culminated in the formation of the RN System Task Force (RNTF) which began functioning January 24, 1986. The RNTF tested and/or cleaned all essential RN heat exchangers per previous commitments to the NRC prior to April 1, 1986. A monitoring / maintenance program for the system was developed, approved, and initisted based on the historical RN system experiences.
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