ML20207S758
| ML20207S758 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 12/14/1983 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Eisenhut D, Mattson R, Speis T, Thompson H, Vollmer R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML17325B782 | List:
|
| References | |
| FOIA-84-741, FOIA-84-742 NUDOCS 8703200246 | |
| Download: ML20207S758 (4) | |
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UNITEJ STATES I
NUCLEAR REZULATORY COMMISSION a
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j WASHINGTON, C. C. 20555 k *... p#
December 14, 1983
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MEMORANDUM FOR:
Darrell G. Eisenhut, Director Division of Licensing Roger J. Mattson, Director Division of Systems Integration Themis P. Speis, Director Division of Safety Technology Richard H. Vollmer, Director l
Division of Engineering
\\
I Hugh L. Thompson, Director Division of Human Factors Safety FRON:
Harold R. Denton, Director Office of Nuclear Reactor Regulation
SUBJECT:
DIABLO CANYON - ALLEGATIONS rhe staff has been directed by the Comission to provide a status report on all outstanding allegations related to the Diablo Canyon plant prior to authorization of criticality and low-power testing. A management plan has been developed and is being implemented to accomplish this objective. Please provide any new information relating to this task to Darrell G. Eisenhut no later than December 16, 1983.
Information of interest includes new concerns, allegations, and additional information on previous allegations. New infor-mation received after December 16 should be provided to the Division of Licensing upon receipt.
If you have questions regarding these items, please contact G. E. Edison in
,DL at X28933.
[
Harold R. Denton, Director I
Office of Nuclear Reactor Regulation cc:
T. Bishop G. Knighton m
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UNITED STATES NUCLEAR REGULATORY COMMISSION 3+
- I wAsHWGTON, D. C. 20565 W* * * * * /
JUN 2 01983 Docket No. 50-275 MEMORANDUM FOR: Thomas M. Novak, Assistant Director for Licensing, Division of Licensing FROM:
L. S. Rubenstein, Assistant Director for Core and Plant Systems, Division of Systems Integration
SUBJECT:
DIABLO CANYON - REVIEW AND SAFETY EVALUAT. ION OF THE COMPONENT COOLING WATER SYSTEM (TAC 49935)
As requested in Darrel'1 Eisenhut's February 18, 1983 memorandum Enclosure 1 is the Auxiliary Systems Branch's (ASB) safety. evaluation report (SER) concerning the reevaluation of the Diablo Oanyon component cooling water system (CCWS). This SER is based on ASB's rereview of the Diablo Canyon FSAR, a site walkdown conducted on January 12, 1983, information obtained during meetings with the applicant on January 28, 1983 and April 19, 1983, and letters from the applicant" dated March 15,1983, March 18,1983, March 25,1983, April 4,1983, April 7,1983, April 15,1983, May 3,1983, and 4
May 18, 1983. ASB has addressed in the SER the following four points identified in the February 18, 1983 memorandum:
1.
CCWS design compliance with FSAR comitments.
2.
CCWS design compliance with applicable NRC regulations.
3.
CCWS design compliance with criteria in the current SRP (Section 9.2.2).
4.
Generic implications of the above determinations regarding adequacy of the Diablo Canyon design approach and philosophy.
In summary, we conclude that the applicant has satisfied the original FSAR comitments and applicable regulations with the CCWS design. However., con-firmation of comitments made regarding the following items as discussed in detail in the SER is required:
1.
Incorporation of a technical specification governing CCWS operation when ocean water intake temperatures exceed 64*F.
2.
Verification of the validity of the currently approved accident analyses for a 64*F intake temperature.
3.
Assurance of an accurate and continuous ocean water temperature monitoring program.
t 4.
Verification of acceptable CCWS operation with two CCW heat exchangers on line under the newly assumed conditions.
Contact:
J. Wermiel X29462 i
10 e o9
l JUN 2 01333 i.
LThomas M. Novak Additionally, we have reviewed the design against the current SRP.
There are three areas as follows wherein the Diablo Canyon CCWS does not meet the current criteria of SRP Section 9.2.2 as identified in the SER:
1.
Moderate energy pipe crack leak rate (BTP ASB 3-1).
2.
Tornado missile protection for the CCW surge tank.
3.
Protection of reactor coolant pumps from multiple locked rotor accident due to loss of CCW.
We have also addressed in the SER the generic implications of the above deter-minations regarding the adequacy of the design approach and philosophy for the CCWS. A sunnary of,the above findings is contained in the Conclusion section of the SER.
In addition, we have addressed those allegations by Mr. Smith regarding the adequacy of the Diablo Canyon CCWS. These allegations concern the seismic design capability of the CCWS, CCWS heat removal capability following a LOCA and concurrent single failure, surge tank level instrumen-tation design, and the nonseismic Category I post-accident sample cooler added to the CCWS vital loop A.
We believe our SER has satisfactorily resolved these concerns.
Details of the allegations whYch do not involve the CCWS follows:
1.
Regarding Mr. Smith's concern with design classification of instrumentation at the plant.
ICSB has reviewed information made available during the meeting of January 28, 1983, and has found it acceptable.
Their evaluation and comments are presented in Enclosure 2.
2.
Regarding Mr. Smith's concerns with the seismic qualification of the diesel generator air intake and exhaust piping, silencers and filters, the applicant indicated during the January 28, 1983 meeting that an evaluation of these components against seismic Category I criteria was underway, and corrective action would be taken as necessary to assure their seismic integrity. Acceptability of this will be confirmed in the IDVP Phase I l
review.
3.
During the January 28, 1983 meeting, the applicant also infonned us that they have verified the seismic Category I capability of the lube oil filters and piping on the safety injection pump. We consider this matter to be resolved.
l 4.
Based on the discussion contained in the transcript of the meeting with l
Mr. Smith on January 6,1983, we believe that arguments were presented that satisfactorily resolved the concern with the non-Class lE design for the reactor protection system trip circuitry.
t
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- - - - - - ~ -
JUN 2 01983 Triomas M. Novak 5.
Based on the discussion contained in the transcript of the meeting with Mr. Smith held on January 6,1983, we believe his concern regarding proper documentation and understanding of the acceptance criteria used during the seismic interaction program (SIP) review at Diablo Canyon was resolved in his own mind by the conservative results applied in the plant design from the SIP evaluation.
The above discussion is our understanding of the status of the evaluation and resolution of the individuals' cen: erns with the Diablo Canyon design to date.
Our review of the Diablo Canyon CCWS is complete.
knN f&
L. S. Rubenstein, Assistant Director for Core and Plant Systems Division of Systems Integration
Enclosures:
-As stated cc w/ enclosures:
H. Denton M. Fliegel E. Case A. Vietti R. Vollmer T. Dunning D. Eisenhut H. Schierling R. Mattson B. Buckley R. Capra H. Thompson R. W. Houston J. P. Knight
- 0. Parr R. Engelken G. Knighton J. Martin
.F.
Rosa J. Wermiel R. Lobel R. Ballard R. Bosnak l
t ENCLOSURE 1 SAFETY EVALUATION OF THE DIABLO CANYON COMPONENT COOLING WATER SYSTEM AUXILIARY SYSTEMS BRANCH 9.2.2 R ea c t o r Aux i l i_a ry_Co o l i na Wa_t e r System ( C o mp_o n,e n t Coolina Water System 3 B A cra n nit un 1
Current Acceptance criteria The current acceptance criteria for the component cooling water system (CCWS) are General Design Criter.ia (GDC) 2, 5, 44, 45 and 46 as di'sYussed in the Standard Review Plan (SRP), NUREG-0800, Revision 2, dated July 1981, Section 9.2.2.
GDC 5 does not apply to DiabLo Canyon since each unit has its own CCWS.
Although not ident'ified in'SRP Sect ion 9.2.2, a l L s a f ety related systems are also required to meet GDC 4.
This review is normally covered in other SRP sections for alL safety related systems and would include the CCWS.
Acceptance Criteria at the Time of the Original _ Review While no SRP existed, the above acceptance criteria were applicable to Diablo Canyon at the time of its initial operating License review (1974) and apply as welL as to current Licensing reviews.
In meeting the above regula-tions, various specific design criteria are compared
,,ch->f;C'C-25 f'
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against the CCWS design.
These criteria have changed since the initial Diablo Canyon review was completed.
This is discussed in more detail in this SER.
The following is a comparison of the Diabto Canyon CCWS to the current acceptance criteria as described in the review procedures o f SRP Se c tiony9.2.2'-and-a s--i nter pre t'ed d.heb. t h e plant was rev.iewed in 1974.
System _Deseeintton The CCWS at Diablo Canyon is designed to provide cooling water to essential and nonessential ' components and to I
operate in atL plant operating modes', including normal power operation, ptant.cootdown and emergencies including LOCA.
The CCWS consists of a baffled s~rge tank, three u
i pumps, two heat exchangers and three cooling loops, (vital.
l i
- ~'
Loops ~A and B and nonvita'l loop C).
The CCWS is provided with redundant radiation monitors to detect inteakage of radioactive fluid from potentialLy radioactive components cooled by CCWS.
Makeup to the CCWS surge tank is normalLy provided by the nonseismic Ca t ego ry I (non Hosgri) deminera-Lized water makeup system.
A seismic Category I (Hosgri) source of makeup water is availabte at a rate of 250 gpm from the condensate storage tank via seismic Category I piping and the makeup water transfer pumps which are powered f rom th; vitial,egecgency_ power. supplies.
Additional
, i.
. nonseismic Category I makeup sources are also provided.
Two normally isolated chemical addition tanks are provided, one on each pump discharge header.
The CCWS pumps are powered from the vital emergency power supplies.
Cooling water to the CCQ' heat exh'cangeri is' provided from redundant trains of the safety-related auxiliary salt water system which trahsfers the heat to the ultimate heat sink (the Pacific Ocean), thereby assuring heat removal in atL modes of operation.
One the CCW heat exchangers is normally valved by closing'a motor operated valve at out the CCW. heat exchanger outlet.
The three CCWS pumps are normalLy headered together at the suction and discharge, of the pumps with separation capabilitf available via local-manually operated valves.
Each pump is provided with a discharge Line to two headers, one supplying the A' vital loop and one to the B vital foop.
Thus', al,i three pumps a're nor'malLy connected
.to both vital' loops.
One CCW heat exchanger is located on each of the above headers.
One or two CCW pumps are nor-malLy operating with two pump. operation preferred.
l Flow through the A header from the pumps passes through the A f
CCW heat exchanger with a local manually operated isolation I
valve at the intet and a motor operated valve at the outlet.
l Header B is lined up in the same manner.
Downstream of the motor operated isolation valves (one is normalLy closed),
headers A and B are crossconnected vic two nori. ally open Local-i r
~,
e n.-
manual iso (ation valves.
Downstream of the header piping cross-
.onnect", vital loops A and B each supply their respective safety related Loads.
Between the two manually operated valves in the cross-coneect piping, nonvital loop C is supplied via a normalLy open motor operated valve,
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- Each vital'L6op (A add B) supplies cooling water,to the fotlow-ing redundant sa f ety rela ted components:
charging pump Lube a
~
oil and seal coole~r, a safety injection pump Lube oil and seal cooler, an RHR heat exchanger, an RHR pump seal cooler and containment air coolers.
Vital loops A and B are. identical except that loop A supplies two containment air cootecs while Loop B supplies three, and, Loop A normalLy provides cooling water to two CCW pump Lube oil coolers and stu'ffing boxes while toop B provides coolingetc..one.
One train of the above com-ponents (inctuding three containment air coolers) is required for safe shutdown under emergency (LOCA) operating conditions.
Nonvital loop C supplies cooling water to the following nonsafety I
related components:
spent fuel pool heat exchanger, Letdown and excess letdown heat exchangers,
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steam generator blowdown heat!
exchangers, reactor coolant pump bearing oil coolers, seal cooters and seal water heat exchanger, sample heat exchanger, waste concentrator cooters, boric: acid evaporator cooters auxiliary steam drain receiver vent condenser, reactor vesset t
.. ~.
~5-t support coolers, reciprocating charging pump coolers, and waste i
gas compressor coolers.
The above components are not required for safe shutdown under emergency operating conditions.
EVALUATION Seismic Clasifficat4Wi FSAR Section 3 indicates'that at L CCWS piping abd components are designed to seismic Cate' gory I requiremends. 'Further, the piping and essential components on vital loops A and B are Quality Group C.
The P& ids show no design classification chance at any CCWS components," including heat exchangers supplied by nonvital
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Loop C.
However, the following statement in FSAR Section 9.2.2 tends to contradict the above, "Excspt for nonvital components.
in loop C and the chemical addi tional t'anks, t.h.e 'CCW system is Design Class 1 (seismic Category I) system."
Our original a
interpretation of this statement assumed that " components" r e,f e r re d t o th'e nonvi t a l L o a'd i t s e.l f, no t the CCWS pressu,re retai.ning portion'of the component.
Therefort, it was assumed in our -original review that the entire system including the pressure retaining portion of the Design Class II toop C c o npo n e n t s wa s d es.f gn'e d t'o.. s e i s m'.i c Ca t e g o r.y 'I c r it e r i a f o r'J pressure boundary purposes.
Thus, a safe shutdown earthauake (SSE) would not cause a failure in the system which would result in loss of water, and isolation of loop C in an SSE was therefore, l
~
t not considered necessary.
The CCWS is located in seismic Cate-gory I structures except for a portion located in the turbine building.
The applicant indicated in the FSAR that this portion of the turbine building is designed not to f ail in anSSE.
This is being verified in~~ Phase I of the Diablo Canyon IDVP.
Refer to the IDVP SER for, details of this issue.
We concluded in our originaD review that the' requirements of EDC 44 regarding the CCWS cooling capability-folLowing an SSE were met.
learned in a" meeting.with the applicant on January,28, 1983, We that our above original conclusion may not have been correct and that the pressure retaining portion of certain nonvital loop C components may not meet seismic Categ'ory I cr.iteria.as we originally assuaed and as was confirmed by the applicant as the design basis for the CCWS.
In response to this concern, by L e,t t er da t e,d 'Pfay 18, 1983, t,he applicant ve'rif*ed that th,e pressure boundarie's of all nonvital loop C components have been reanalyzed to assure their integrity under pos.ulated SSE con-ditions.
Thus, a postulated single failure (to close) in the C Loop supply remote manual motor operated valve wilL not result in an unacceptable condition as isolation of the C Loop folLoving an SSE is not essential for assuring CCWS safe.y function.
Local manual action can be taken to close the valve as necessary.
FolLowing an SSE, the operator would take Local manual action to transfer makeup to the CCW surge tank from the normal nonseismic Category I domineralized water makeup system to the seismic Category I condensa te storage and transf er system.
Since no increase in leakage folLowing an SSE occurs, no critical time constraint was placedon this manual action.
It.should be further noted that Phase II of the Diab Lo. Canyon,IDVP is also considering the above concern.
In addition, we were informed during the January 28, 1983 meeting that the post accident sample cooter
't recently added to.the A vital Loog, vill be qualified to seismic Category I criteria.
s indicated above, confinmati n of our original acceptance of the CCW design in this area has been
-^
provided.
Therefore, we conclude that. the require ~ments of GDC 2 and 44 and the guidelines of Positions C.1 and C.2 of Regulatory Guide 1.29 regarding seismic classification are met.
Leakage Desion Because of our original conclusion regarding the futt seismic i
Category I qualification of the pressure boundary of the CCWS, i
acceptance of system Leakage was originally based on a postulated nonmechanistic moderate energy pipe crack which was the 200 gpm Leak rate assumed by the applicant in the FSAR.
It was shown by the applicant that the operator had 20 minutes under the above assumed leakage condition to act and isolate nbnvital
.g.
i Loop C or separate the two vital loops in order to assure proper CCWS operation.
To isolate loop C at the supply, the motor operated isolation valve must be closed either remote or local manually or the Local manual. cross-connect valves must be closed.
To isolate Loop C at the return header,.since there are no j
check valves, the two local manual cross-connect valves at the CCW pump suction must be closed.
Closing these valves renders one of the CCW pumps (pump 1-2) inoperable since it can only take suct' ion from the loop C return header.
Similar manual actions are required if.,the crack is assumed in either vital Loop A or B.
No concurrent single failure is assumed with a mode' rate energy pipe crack in a moderate energy dual purpose system such as the Diablo Canyon CCWS as identified in the criteria of Branch Technical Position (BTP) ASB 3-1.
4 However, because of the size of the CCW Loop headers, 20" for the A, B and C Loops, and 30" for the A and B headers, a ' crack postulated in accordance with'BTP ASB 3-1 would result in a i
higher flow rate than the assumed 200 gps.
The applicant pro-vided no bases or detailed evaluation for a maximum Leak rate of 200 gpa.
Local manual valves must be closed at both the supply and return headers, or suf ficient makeup provided to keep up with the loss of water.
To demonstrate compliance with current SRP criteria, the' applicant shoutd pr'ov'ide's more ~ complete m
.,,___,m-___.7m._,._
-9 analysis that adequate time exi,sts for operator action to prevent damage-to att the CCW pumps on Loss of suction and that a tem-porary comptete loss of CCW system flow while the operator realigns the system is acceptable assuming the greater L eak We have noted in a field watkdown that the A, B and C races.
Loop supply valves are Located in one area and are readily a c ce ssible' 3or local"$anual operation as r eq uir ed.
I
~
Based on'the above3 we cannot conclude th t the CCWS meets the eurrent criteria of BTP ASB 3-1 concerning moderate energy pipe break protection and therefore, does not meet our current inter.
pretation of the require'mVnts of GDC 4.
However, we a'pproved the applicant's assumed Leak rate as an exception to the moderate energy pipe break criteria in our original review on the basis-that a 200 gpm Leak rate was large enough to dem'onstrate a
~
satis-factory design capability.
Indication of leak rates mQch'tess 4
than 200 gpm would be detected and action takeb before a Leak rate of this a' mount would dehelop.,
We believe the above ' deter-mination is stitL 'true and th,at GDC 4 and 44 with respect to Leak det1ction and isolation capabilities are met.
Instrumentation Desien The instrument and control s'ystems for the CCWS that perform saf ety f unctions are seismically and environmentally qualified.
The saf ety functions include those actions required for design basis accidents.
In addition, the diagnostic instrumentation which provide indication of temperatu re and pressure to confirm that the.CCWS is performing its safety function is also qualified
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for seismic and environmental conditions.
Instrumentation which d:es not perform a safety fonr+4-a
=ad 3-l
As indicated previously, the applicant has verified that the CCWS presdure boundary integrity is maintained fotLowing a1SSE,'
and thus no additional Leakage was assumed fotLowing a1SSE.
The applicant's original analysis indicates that operators have sufficient time to isolate the nenvital components and thereby insure the continued operabilit'y of the. essential p'or-tions of the CCWS under the' assumed non~ mechanistic Leak' IowlevelalarmsareprovidedontheCCWsurgetanks rate.
~ which would identify that a f ailure of the DCWS pretsure ' boundary
~
had occurred.
The level switches and alarms were. originally designed and installed 'to' Class 1E standards, includingsehsmic qualification to assure th.eir operability fo t Lowing a seismic event.
Because no additional Leakage is assumed to result from the SSE, immediate operator action is unn'e'cessary, and thus the Level instrumentation is not viewed as performing a
safety function.
The operator can realign CClj surge tank to th[' seismically qualifie'd source some time subsequent m ak eup to the earthquake.
Therefore, the CCW surge tank Level indico-tor i's classified as Class 1C under the Diablo Canyon instru-ment classification system, which only requires that it main-tain its pressure boundary following anSSE.
The staff finds the design and classification of the CCW surge tank level instrumentation acceptable because the integrity of the GCWS Loop t pressure boundary is maintained fotLowing riSSE and i
innediate operator action is therefore unnecessary.
l
.Missite _P_rotection With the exception of the surge tank, the entire CCWS is located within tornado missile and flood protected structures.
The system is located away from high energy piping systems.
The CCWS pumps are located in separate cubicles thus providing protection from internally generated missiles.
The CCW surge tank is to.c.ated on t,he auxiliary building roof, 105 feet above g round, and is not, f ulLy protected against' tornado missiles.
The app.Licant assumes (FSAR Section 3.3).that only one tornado missile acts at a time.
This does not meet current criteria identifi~ed in SRP Section 3.5.2.
The missile spectrum identi-fied by the applicant meets SRP criteria and is acceptabte, but the "safewind" (maximum sph for a given component) for the surge tank is below that identified in Regulatory Guide 1.76 for tornado Region II.
The applicant provided the results of analyses for the surge tank and its appurtenances.
Based on t he above, we concluded that although the tornado missile pro-tection for.the CCW surge tank do,es not' meet criteria.
~
3.5.1.4, 3.'5.2 and 9.2.2, in our judgement, in SRP Sections the probability of tornado missile damage which would result in CCWS failure was sufficiently low to permit acceptance of the design.
We continue to support this judgement.
We therefore conclude that GDC 4 with respect to missile protection is met.
. Heat Removat Caoabilitv 4
The applicant indicates in the FSAR that one CCW pump and heat exenan er is sufficient to provide decay heat removat and essen-tial component cooling in the event of the most Limiting acci-dent, the design basis LOCA with concurrent loss,of offsite power and a single active failure.
Under such an event, aLL three CC'W pumps are automatically started, the motor operated valve to the nonvital C Loop automatically closes (on receipt i
~
of a high containment pressure signal), and the operator remote i
manually opens the normatty closed motor operated valve to one CCW heat exchanger in order to put both in service.
Twenty minutes for operator action to perform this function is assumed.
In the Long tern post-accident (LOCA) recirculation phas'e, the operator also Locally manually closes the Loop A and 8 cross connection valves to separate the CCWS into fully redundant trains.
Because of the normalLy open cross connection, flow to atL five containment cooters is provided, even though two are on the A Loop and three on the B Loop as previously stated.
The FSAR CCWS heat removat analysis is based on a single failure of one emergency diesel generator (Loss of~ one ' vital bus).
This is the most limiting failure from the standpoint of containment integrity following a LOCA as its results in a simultaneous l
Loss of power to two containment air coolers and core contain-
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ment spray pump..
The FSAR indicates that fotLowing a LOCA under l
, the above assumption, CCW exit water temperature from the con-tainmen,t air coolers is 216.*F.
This is at a flow rate of 2000 gpm through each cooler and assumes that the nonvital loop is i
isolated.
The applicant states in the FSAR that the CCW pres-sure is sufficient to prevent boiling in the CCWS at this temperature.
Return flow from the inoperative containment air cooters mixes with the 216*F water and results in reducing the but k CCW return temperature to a valve below the CCW pump suc-tion design of 171'F.
We accepted the above CCWS heat removal capability analysis in o*uY original SER and concludedthat i
G D C '44 wa s met.
However, concerns have,recently been identified'that the above described CCW heat removal analysis may not be the most limit-i ing f rom the stand'cpoint of CCW cooling performance and flow capacity and their affect on assuring plant safety.
This is particularly true in the event the operator fails to open the valve to the normalLy isolated CCW heat exchanger since one heat exchanger will now experience full CCW pump flow and heat Load for some time.
Furt'her', the~ assumed vital bus' single -
I failure may not be Limiting with respect to assuring a maximum CCW temperature within design limits for equipment cooled by the system.
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In response to these concerns, by Letters dated March 18, 1983, 1
April 4, 1983 and May 18, 1983, the applicant provided the resultd of a reanalysis of the heat removal capability of the CCWS assuming worst design basis heat. Load (LOCA) and the most limiting single failure.
From the standpoint of assuring proper CCWS cooling performance for assuring acceptable equipment operation, it was determined that single f*ailure of an auxiliary' salt water pump results in a higher CCW temperature (with one CCW heat' exchanger in operation) than was determined in the original FSAR hiat'remov.al analysis and is thus more l,imiting.
In order to maintain *CCW supply temperature at the maximum acceptable value of 132*F for equipment operation, a maximum ocean water (auxiliary salt water system) temperature of 64'F must be assumed.
The FSAR analysis assumed an ocean water temperature of 70'F.
Consequently, the applicant has committed to the following in order to assure proper CCWS safety function:
1.
Incorporation of a technical specification on the 64'F ocean water intake temperature with appropriate surveil-Lance, limiting conditions for operation, action statements ahd basis.
The applicant has proposed actions such as valving in the second CCW heat exchanger or reducing plant power level when the intake temperature exceeds 64 F.
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Confirming that the accident analysis previously performe,d at an assumed 70*F ocean water temperature are not affected by'a 64 F value.
0 3.
Assuring accurate and continuous monitoring of the int a k e water temperature.
4 Verification of acceptable CCWS performance.with two heat exchangers in operation under the new assumed conditions.
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We wilL confirm compliance with the above commitment and find 4
them to be acceptable for resolving the concerns.-
The applicant has alsb provided further information which indi-
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cates that the design of the CCWS is such that only a smalt increase in flowrate through one CCW heat exchInger occurs between two and three CCW pump operation.
Further, CCWS pre-operational testing and flushing at excess flowrates has veri-fied proper. CCW and other saf ety r'e' lated heat exchanger per-formance under normal and accident conditions.
In addition, maximum CCW flow under design basis conditions is below the value identified in the CCW heat exchanger specification which was guaranteed by* the equipment vendor.
Pending f ormal documentation of the above identified cor.initments, we conclude that the applicant has provided adequate assurance i
of CCW heat removat safety function and therefore meets the i
i requirements of GDC 44.
Rea ctor_ Coolant Pumo contina The design of the CCW to the reactor coolant pumps (RCPs) does
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not meet our current SRP criteria regarding protection against multiple locked rotor as a single CCW supply and return Line (header) and associated containment isolation valve are provided
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to serve alL four RCPs.
A pipe crack or sin'gle failure in the v a l v e co_u,L d c a u s e L,o s s o f a t L CCW flow to the bearing oil coolers and Lead to a potential pump seizure.
The applicant normalLy would be required to provide the results of RCP tests indicating that sufficient time is available to detect loss of a t L CCW and v
trip the pumps manually before an unacceptable condition occurs.
Saf ety grade indication of Loss of CCW flow to the pumps woutd also be required.
If the above can not.be' demonstrated,.an auto-matic trip of the RCPs on loss of CCW or~ redundancy in the CCW supply and return to the RCPs should be provided.
This criteria was not established at the time of the original Diablo Canyon-r e v'i e w.
Ho w~e v e r, m u l t i p l e L o'c k e d r o t o r w a s v i e w'ed a s a s f f i-ciently low probability occurrence to not require backfit of the criteria to older plants including Diablo Canyon.
We believe this judgement is stilL valid, and therefore the above I
described design is acceptable.
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A review of the Dia5Le Canyon against the criteria of Items II. K. 2.16 i-and II.K.3. 25 of NUREG-0737 concerning RCP seal cooling with Loss of power has been previousty done and Diablo Canyon found acceptabte.
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Testino and Insoection The CCWS operated continuously in at L plant opera ting modes.
The pumps are rotated in service on a scheduled basis to obtain even wear and are periodically tested and inspected in accor-dance with plant Technical Specifications.
The system components are located in accessible areas to permit inservice inspection as requi_ red.
Thus, the requirements of GD;C 45 and 46 regarding inservice inspection and testing are met.
Conclusion Based on the above, we o clude that the Diablo Canyon CCWS satisfies the originally FSAR commitments and conclude that the requirements of GDC 2, 44, 45 and 4.6 r~egarding protection
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against natural phenomena, cooling water capability, inservice inspection and testing, and the guidelines of Regulatory Guide 1.29 regarding, seismic classjfication are m,et.
We also conclude that the requi rem e,nt s o f GD C' 4 rega rding protec' tion from environmental and missile affects are met.
.The extent of compliance of the CCW with current applicable criteria of SRP Section 9.2.2 is dis-cussed in the evaluation above.
Noncompliances are summarized betow.
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1.
GDC 4 and BTP ASB 3-1 regarding Leakage rate from moderate energy pipe cracks.
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2.
GDC.4, Regulatory Guide 1.76, and SRP criteria regarding tornado missile protection (unprotected CCW surge tank).
3.
SRP criteria regarding protection of the RCP.t from multiple Locked rotor, accident due to loss of CCW.
We conclude that thkse deviations are acceptable as discussed in the evaluation above.
It should also be noted that the CCWS is the only safety related elo. sed ' Loop cooling wat'fr system we have identified at Diablo Canyon which also serves nonessential components.
Thus, the above identified concerns which required subsequent reevaluation shoutd appty onty to the CCWS, and thus no generic implication is involved.
Further, the work underway in the Diablo Canyon IDVP should provide additional insight into the adequacy of the applicant's design approach and ph-itosophy for safety related systems with respect to applicable NRC criteria.
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ENCLOSURE 2 COMMENTS CONCERNING DIABLO CANYON INSTRUMENTATION DESIGN WITH REGARD TO THE TRANSCRIPT OF THE MEETING WITH JOHN SMITH AND NRC STAFF HELD JANUARY 6, 1983 A concern was noted that some aspects of the instrumentation and controls for the component cooling water system were designed from seismic standpoint which only assured that they would not fait a
dn a manner to break the pressure boundary of the CCW system.
As a portion of' the CCW system supplies cooling water to nonvital components, i.e.,
"po'tentia,L,Ly nonseismicalLy qualified components which do not perform a safety function, the concern appears to center on how plant safety is maintained following a seismic event.
In particular, Mr. Smith was told by someone withi,n PG8E or Bechtel that the Level switches on the CCW surge tanks were only clas-sified as seismic from a pressure boundary standpoint; i.e.,
their operability to provide alarms fotLoving a seismic event is
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not assured.
At the meeting held between PG8G and the staff on January 28, 1983, the Licensee stated that levet switches and alarms were originally qualified to Class 1E requirements, including seismic considera-tions.
However, within the PG8G system of classification for instrumentation, these instruments are Class IC, i.e.,
they only i
. required seismic qualification from a pressure boundary standpoint.
Further, it was noted that these instruments were not included in subsequent reviews of the seismic design adequacy (Hosgri) such that these instruments could be reclassified as IB in the Diablo Canyon classification system.
Class IB includes se.ismic quali-fication to insure operability in addition to pressurs boundary considerations.
At the January 28, 1983 meeting with PGSE, the Licensee stated that the designers concluded?that the nonessential components in nonvital loop C would not fait in a design basis seismic event.
Further, additional analysis and eva Lustions have been made to co n f ie rm that this judgement is valid.
Based on this, it wduld appear that one may now conclude that a design basis seismic event wilL not result in a loss of the pressure boundary of the CCW system and this need not be considered a design basis ev.ent for functional availability of the CCW surge tank level instrumen-tation.
Therefore, the PG8G classification of Level switches and alarms as 1C, (pressure boundar'y integrity only) is appropriates l
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O A+ If the original design'of the CCW system had included all components as seismic Class 1, its pressure boundary integrity would not have been questioned for a seismic event.
Therefore, PG&E's approach was to conduct additional analysis and evaluations to provide assurance that the CCW pressure boundary wiLL not fail in a seismic event.
The Licensee has stated and the Diablo Canyon SER note's that instru-mentation and control components required to perform a safety function are designed to ne'er seismic Category I requirements.
The problem as can be seen from the above is those judgements which go into the assessment of what constitutes a required safety-I function.
Although further effort has been made t'o confirm'such 4
judgements in the case of the CCW system, it is assumed that based on the review of the Diablo Canyon FSAR and subsequent independent design reviews, that appropriate judgements were made for the balance of instrument and control system seismic classifications at Diablo Canyon.
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