ML20072L265

PG&E Opposition to San Luis Obispo Mothers for Peace Renewed Motion to Reopen Record.* Util Opposes San Luis Obispo for Peace Motion Based on Affidavit Stating No Evidence Found in Motion Re Flaw in Program.W/Certificate of Svc

ML20072L265
Person / Time
Site:	Diablo Canyon
Issue date:	08/23/1994
From:	Repka D PACIFIC GAS & ELECTRIC CO., WINSTON & STRAWN
To:	Atomic Safety and Licensing Board Panel, SAN LUIS OBISPO MOTHERS FOR PEACE
References
CON-#394-15622 50-275-OLA-2, OLA-2, NUDOCS 9408310156
Download: ML20072L265 (123)

Text

(

g DDcKEIL.D Auh 3, 1994 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION O

BEFORE THE ATOMIC SAFETY AND "

LICENSIN@FFlO BOARDha tt i ll " i UP

[9(phCh In the Matter of: )

Pacific Gas tend Electric Company

} Docket Nos. 50-323-OLA 50-275-OLA_ L

)

) (Construction Period (Diablo Canyort Nuclear Power ) Recovery)

Plant, Units 1 and 2) )

)

PACIFIC GAS AND ELECTRIC COMPANY'S OPPOSITION TO SAN LUIS OBISPO MOTHERS FOR PEACE RENEWED MOTION TO REOPEN THE RECORD I. INTRODUCTION On August 8, 1994, almost one year after the record was closed in this proceeding, the San Luis Obispo Mothers For Peace

("MFP") filed a Motion to reopen the record.I' Pacific Gas and Electric Company ("PG&E") herein responds in opposition to the Motion .2/ As discussed below and in the attached Affidavit of Michael J. Angus (Attachment 1) (" Affidavit") , the Motion offers no evidence of any fundamental or current flaw in PG&E's maintenance and surveillance programs. Nor does the Motion present any evidence that the public health and safety was, or could have been, l' " San Luis Obispo Mothers for Peace's Renewed Motion to Reopen the Record Regarding Pacific Gas and Electric Company's Application for a License Amendment to Extend the Term of the operating License for the Diablo Canyon Nuclear Power Plant,"

dated August 8, 1994 (" Motion").

2/ As confirmed by the Licensing Board, service of MFP's Motion was by mail and this opposition is timely filed in accordance with 10 C.F.R. SS 2.730(c) and 2.710.

9408310156 940823 PDR Q

ADOCK 05000275 PDR ,

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l adversely affected by the engineering deficiency on which the Motion is based. At bottom, the Motion raises no matter that could affect the outcome of this proceeding. Under the Commission's  ;

Rules of Practice, 10 C.F.R. S 2.734, MFP's Motion must be denied.  !

Under the Commission's reopening standards, the Motion is -

fatally flawed in that it offers no independent evidence by competent or expert individuals with knowledge of new facts.

Instead, MFP relies solely on NRC inspection documents which on their face contradict the arguments of the Motion. As is clear ,

from the NRC correspondence, all of the unresolved or followup inspection issues related to this matter and cited by MFP have been j closed as regulatory issues, with a single Notice of Violation

("NOV"). The NOV itself fails to raise a programmatic mainte'1ance deficiency and has, in any event, been addressed by PG&E. In its March 1994 decision on MFP's previous motion to reopen, the Licensing Board allowed MFP to later file a new motion to reopen i

based on any matters that have been demonstrated as significant and that have substantive implications with' respect to maintenance and surieillance programs. However, using these criteria, the matter cited by MFP does not support reopening the record.

i In evaluating MFP's Motion, the Licensing Board must keep in mind a central tenet enunciated by the Commission under the  :

Atomic Energy Act: perfection is not required-for issuance of a license, or for a license amendment such as that at issue here.

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Rather, what is required is reasonable assurance that the licensed i

facility can and will be operated without endangering the public '

health and safety. In this license amendment proceeding, the admitted contention concerns solely the adequacy of PG&E's l

maintenance program, which was examined exhaustively during two I weeks of hearings completed in August 1993. During those hearings, MFP attempted to show a number of maintenance deficiencies suf ficient to indicate a breakdown in PG&E's overall implementation of the program. However, overwhelming contrary evidence --

programmatic as well as issue-specific -- refuted MFP's hypothesis.

There must be finality in the Commission's proceedings, especially in light of the Commission's on-going inspection and enforcement program, which assures that future problems are identified and corrected. The single NOV concerning PG&E's engineering work in one case fails to prove a programmatic problem with the plant's maintenance program and fails to justify reopening the record.

II. BACKGROUND In July 1989, the NRC issued Generic letter ("GL") 89-13,

" Service Water System Problems Affecting Safety-Related Equipment,"

addressing the potential for biofouling of service water systems.

PG&E responded to the recommendations of GL 89-13 and, among other things, implemented a monitoring program for the Auxiliary

, Saltwater ("ASW") system at the Diablo Canyon Nuclear Power Plant i

("DCPP"). Affidavit at 1 13-14. PG&E also performed, in 1991, I

one-time ' heat exchanger performance testing of the Component e

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Cooling Water ("CCW") heat exchangers. M. at 1 14. And, in 1992, PG&E implemented a continuous chlorination program that has been effective in controlling biofouling that might otherwise affect service water system performance. M. at 1 15.

MFP's Motion is nominally based upon an NRC enforcement action issued to PG&E on July 14, 1994.2/ The enforcement action  :

cites a single violation of 10 C.F.R. Part 50, Appendix B, Criterion XVI, for PG&E's untimely engineering response to an unresolved issue related to the past operability of the ASW I system.f' Specifically, the February 1991 GL 89-13 test data for the CCW 1-2 heat exchanger suggested that the heat exchanger (one  !

of four) was performing at 1.3 percent below design (nameplate) heat transfer capability. The test results for the other three CCW heat exchangers indicated that those exchangers met their design basis requirements. PG&E's engineering judgment at the time was, based on the collective results of the tests for all four heat exchangers, as well as the similar design of the heat exchangers and the uncertainties of the test methodology, that the CCW 1-2 F Enforcement Action (EA)94-056, " Notice of Violation (NRC Inspection Report No. 50-275/94-08, 50-323/94-08)," dated July 14, 1994 ("NOV"), and served on the Licensing Board and parties by NRC Staff counsel under a cover letter dated July 22, 1994.

i' Criterion XVI provides that measures be established to assure that " conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and '

equipment, and nonconformances are promptly identified and corrected." i heat exchanger could meet its design basis. Affidavit at 1 16.

However, a PG&E Quality Assurance ("QA") audit subsequently raised the issue of the adequacy of the engineering judgment to resolve the matter. Despite this QA audit item, documented in a May 1993 Action Request and a July 1993 audit report, PG&E -- through its engineering organization -- had not, as of the time of the NRC Staff's December 1993 inspection, timely assessed the test result.

Id. at 1 5. According to the NOV, this lack of a timely assessment was poor engineering and a violation of Criterion XVI.

The NOV did no_t, however, cite any violation related to either the past or present operability of the ASW system or the heat exchangers. Likewise, the NOV did Eqt cite any current deficiency in the operation, testing, or maintenance of service water systems or components. Indeed, the NRC has never suggested that there has been any biofouling problem at DCPP since implementation of continuous chlorination in 1992. The NRC has, in fact, previously observed that the continuous chlorination now relied upon is very effective in controlling heat exchanger biofouling. See NRC Inspection Report Nos. 50-175/93-36 and 50-323/93-36, dated January 12, 1994 ("IR 93-36"), Details at 3.

As discussed in the attached Affidavit, prior to issuance of the NOV PG&E also specifically evaluated the issues raised by the February 1991 CCW heat exchanger test data. PG&E's evaluation showed, among other things, that the CCW 1-2 heat exchanger

actually operated at 101 percent of the design (nameplate) rating at the time of the test with a 95 percent confidence level.

Affidavit at 1 17. Further, new performance tests conducted in April 1994 concluded that the CCW 1-2 heat exchanger is currently operating at 116 percent of its design capability (i.e., with significant margin). M. at 1 18. Finally, PG&E's comprehensive evaluations confirmed (1) the current operability of the ASW system and the CCW heat exchangers, (2) the adequacy of the current operating, testing, and maintenance practices (including continuous chlorination), and (3) the low actual and potential safety significance of certain bounding biofouling conditions that predate full implementation of the GL 89-13 recommendations. M. at 1 19-20.

PG&E also responded to the NOV, on August 5, 1994.I' PG&E's response identified the corrective actions to prevent recurrence of problems with untimely engineering reviews. As noted in that response, PG&E is presently in full compliance with the NRC requirements at issue. The NRC Staff has accepted PG&E's reply to the NOV, stating that the reply was " responsive to the concerns raised in our Notice of Violation."F It is also important to l' pG&E Letter DCL-94-174, " Reply to Notice of Violation in NRC Enforcement Action 94-056," dated August 5, 1994 ("NOV Reply"). A copy is included as Attachment 2 hereto. S_eg e also Affidavit at 1 7.

F NRC Letter from K. E. Perkins to G. M. Rueger, "NRC Inspection Report," dated August 10, 1994. A copy is included as l Attachment 6 hereto. S_en Affidavit e at 1 8. l l

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emphasize that the matter addressed in the NOV was an engineering performance issue, nqt a maintenance issue, surveillance issue, or equipment operability issue. Therefore, the matter has little bearing on Contention I in this proceeding, which addresses the scope and effectiveness of the DCPP maintenance and surveillance programs. By the same token, to the extent that MFP's Motion j raises issues other than the timeliness issue, such as inspection issues previously closed out by the NRC Staff, the Motion finds no support within the NOV.

MFP's Motion is styled as a renewal of its prior motion of February 25, 1994,2' which was based upon NRC IR 93-36. In IR 93-36, the NRC inspector (Paul P. Narbut) had identified eight discrete " unresolved" or followup" items regarding ASW system biofouling and heat exchanger testing. Those unresolved issues were the subject of a detailed response from PG&E, dated February 15, 1994.!' The issues were subsequently narrowed in NRC l Inspection Report 94-08, dated March 16, 1994. In IR 94-08, the Il " San Luis Obispo Mothers for Peace's Motion to Reopen the Record Regarding Pacific Gas and Electric Company's Application for a License Amendment to Extend the Term of the Operating License for the Diablo Canyon Nuclear Power Plant,"

dated February 25, 1994.

l l' PG&E Letter DCL-94-037, " Auxiliary Saltwater System Operability," dated February 15, 1994 ("PG&E Response"). A copy is included as Attachment 3 hereto. This response is described in detail in PG&E's response in opposition to MFP's original motion. See " Pacific Gas and Electric Company's Reply in Opposition to San Luis Obispo Mothers for Peace Motion to Reopen the Record," dated March 7, 1994.

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NRC Staff indeed identified three of the original issues as

" apparent violations" to be discussed at an enforcement conference.

IR 94-08, however, closed out as resolved all other issues that had been identified in IR 93-36.2' MFP's original motion was then denied ie Licensing Board on March 23, 1994, without prejudice to MFP later filing a motion to reopen " based on matters that have been demonstrated as significant and possessing substantive implications with respect to implementation of the maintenance / surveillance program" at DCPP.B The NOV now relied upon by MFP was then iscued by the NRC and identified only the one violation previously discussed, which related to the timeliness with which PG&E's engineering staff had addressed the questions raised by the February 1991 test results for the CCW 1-2 heat exchanger. Contrary to the Licensing Board's decision in LBP-94-9, MFP in its renewed Motion attempts not only to imbue this NOV with relevance and significance for this proceeding, but also attempts to resuscitate various issues from IR 93-36 that were not the basis for any enforcement action. These issues were specifically closed out by the NRC Staff in IR 94-08 and thus do not meet the Licensing Board's threshold for allowing a new motion to reopen based on the subsequent enforcement action.

2' S_qq cenerally NRC Inspection Report 50-275/94-08; 50-323/94-08, dated March 16, 1994; see Affidavit at 1 9.

8 " Memorandum and Order (Ruling Upon Motion to Reopen Record) ,"

LSP-94-9, dated March 23, 1994, slip op. at 5 (footnote omitted).

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Moreover, contrary to MFP's claims, neither the NOV itself nor these other now-resolved issues provide a safety basis that would warrant reopening the record of this proceeding. Under the heavy burdens imposed by 10 C.F.R. S 2.734, MFP's Motion must be denied.

III. ARGUMENT A. The Acoljcable Lecal Standard Imooses a Heavy Burden The Commission's standard for reopening the record of an i evidentiary proceeding is established in 10 C.F.R. S 2.734. A motion such as MFP's must satisfy all of the following criteria:

(1) The motion must be timely (S 2.734 (a) (1)) ;

(2) The motion must address a significant safety or environmental issue (S 2.734(a) (2));

l (3) The motion must demonstrate that "a materially different result would be . . . likely had the newly proffered evidence been considered initially" (S 2.734 (a) (3)); and (4) The motion must be accompanied by affidavits, "given by competent individuals with knowledge of the facts alleged, or by experts in the disciplines appropriate to the issues raised," supporting the movant's claims with respect to the prior three criteria (S 2.734 (b)) .

The Commission's reopening standard draws upon and amplifies longstanding Commission jurisprudence which stresses the

" heavy burden" on a motion to reopen the record. Egg, e,q,, Kansas GA3_an.d Electric Co. (Wolf Creek Generating Station, Unit ~ 1) , ALAB-462, 7 NRC 320, 338 (1978); Pacific Gas and Electric Co. (Diablo Canyon Nuclear Power Plant, Units 1 and 2), ALAB-756, 18 NRC 1340, 1344 (1983). The eopening burden is not equivalent to that involved in pleading contentions; that is, the rule requires the proponent to bring evidence (i.e., an affidavit from a competent witness), not just to raise issues.H' The Licensing Board must then take a "hard look" at the evidenqq offered, as well as any responsive affidavits or exhibits, to determine whether the motion provides a legitimate reason to reopen the record. geg, e.a.,

Public Service Co. of New Hamoshire (Seabrook Station, Units 1 and 2), LBP-89-4, 29 NRC 62, 73 (1989) ("[N]o reopening of the evidentiary hearing will be required if the affidavits submitted in response to the motion demonstrate that there is no genuine unresolved issue of fact, i.e., if the undisputed facts establish that the apparently significant safety issue does not exist, has been resolved, or for some other reason will have no effect on the outcome of the proceeding") .u/

n' The Commission has also ruled that a movant in seeking to meet l the heavy burden required to justify reopening the record is not entitled to engage in discovery in order to support the

! motion. Rather, the issue is whether the available l information broucht forward b_y .t_hn povant meets the reopening standard. Louisiana Power & Licht Co. (Waterford Steam Electric Station, Unit 3), CLI-86-1, 23 NRC 1, 6 (1986),

cuotina Metropolitan Edison Co. (Three Mile Island Nuclear Station, Unit 1), CLI-85-7, 21 NRC 1104, 1106 (1985).

D' S_g_q alg,q Consumers Power Co. (Midland Plant, Units 1 and 2),

LBP-84-20, 19 NRC 1285, 1299 at n.15 (1984) ("Unlike with I respect to a new, timely filed contention, on a motion to reopen the record, we can give some consideration to the  !

substance of the information to be added to the record");

l Vermont Yankee Nuclear Power Coro. (Vermont Yankee Nuclear l Power Station), ALAB-138, 6 AEC 520, 523 (1973).

I

l The Commission, in promulgating S 2.734 in 1986, also recognized the importance of closing the record to achieve finality in the hearing process -- while also recognizing at the same time that the normal NRC inspection and enforcement process would continue. See 51 Fed. Reg. 19535, 19539 at col. 1 (1986), citina ICC v. Jersey City, 322 U.S. 503, 514-15 (1944). The Commission assumed that the NRC Staff will continue to routinely inspect nuclear facilities, find violations, and assure necessary compliance. There can be little doubt, however, that the Commission requires for reopening more than mere recitation of an enforcement issue for which corrective actions to prevent recurrence will necessarily follow (see 10 C.F.R. S 2.201(a)).

Accordingly, the " heavy burden" placed on the proponent of a motion to reopen includes the showing of a tangible contribution, independent of the NRC Staff, of some technically competent testimony that would support the movant's claim. See 10 C.F.R. S 2.734 (b) .

B. MFP's Motion is Untimelv to the Extent it Raises Issues Other Than " Timeliness" MFP's Motion attempts to raise a host of issues related to ASW system biofouling and heat exchanger testing. There are issues purportedly based on the NOV, and others expressly based on IR 93-36. S_e_e e Motion at 10-23. The NOV was issued on July 14, j j

1994, and PG&E makes no claim that the Motion is untimely to the extent it follows from the NOV. However, as discussed above, the

1 NOV cites only one violation related to one issue: the timeliness of PG&E's engineering review of the 1991 heat exchanger test This NOV does not provide an opportunity to reopen other results.

issues identified by the NRC Staff in IR 93-36, but ultimately closed by the Staff or abandoned for enforcement purposes (either l in IR 94-08 or in issuing the NOV). Consistent with 10 C.F.R. S 2.734, if MFP had evidence on these issues independent of the NRC Staff, the time has passed in which MFP could have and should have brought that evidence forward. )

C. MFP's Motion Fails to Provide Evidence of an Issue That is "Sionificant" in the Context of this Proceedina ,

1 Under 10 C.F.R. S 2.734 (a) (2), a motion to reopen must l

address a "significant" safety or environmental issue. Stripped to its essence, MFP's claim of " significance" for the CCW heat exchanger testing matter derives from the fact that the NRC Staff I 1

chose to issue a Severity Level III NOV for engineering associated l

with the testing. Motion at 24. MFP offers no evidence apart from the Staf f's finding. Indeed, MFP has advanced no technical support i

for its other arguments in support of the significance of the issues MFP raises. For example, no support (affidavit or otherwise) is offered for the hyperbolic speculation that "if [the DCPP] cooling system were inadequate to remove heat from safety systems during an accident, those systems could b_q rendered inoperable as a result, with disastrous consequences" (id.

(emphasis added)). Likewise, no support is offered for the bald

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assertion that "this system was out of compliance with [the DCPP) design basis" and that this "is a matter of major safety concern" d

(id.). The fate of the Motion under this S 2.734 criterion turns solely on the " significance" of the NOV.

Turning to the NOV, PG&E agrees with the enforcement

" significance" of even a single Severity Level III NOV. However, the significance of that NOV in the context of this licensing proceeding is an entirely separate matter. This is a proceeding related to construction period recovery. In this context, Contention I focuses on an overall assessment of the maintenance and surveil' lance procrams at DCPP --

not on isolated, historic issues addressed and resolved in the ordinary course of the regulatory process. The NRC regulatory process has ensured that I

the issue raised in the NOV is corrected. Egg Affidavit at 1 7-9.

(Similarly, the NRC Staff has closed out to its satisfaction the other issues previously identified in the inspection reports.)

1 This process precludes the issue from ever maturing into a l significant matter for plant operation during the recovery period at issue.

One Licensing Board, in denying a motion to reopen based upon an NRC enforcement action, specifically observed that an. l enforcement action itself offsets the significance of the issue:

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l The matter became significant in part because of the Staff's strong response which is relied  :

upon by Intervenors as evidence of a  !

significant safety problem. Because of that l strong response, the matter in part loses its  !

significance. The corrective actions produced l by the Staff's enforcement conference, the  !

additional explanatory information provided by  :

the Applicant, and the Staff's monitoring commitment provide reasonable assurance that the matter has been or will be timely resolved.

Commonwealth Edison Co. (Byron Nuclear Power Station, Units 1 and 2), LBP-83-41, 18 NRC 104, 109-10 (1983). Likewise, in the present case, where MFP offers nothing independent of the NRC Staff, the Staff can be relied upon to resolve its own issue.

The Commission has also specifically recognized that ongoing NRC Staff monitoring of an issue undercuts any justification for reopening a proceeding based on that issue. e Sen Cincinnati Gas and Electric Co. (W. H. Zimmer Nuclear Power Station, Unit 1), CLI-82-20, 16 NRC 109, 110 (1982). Just as in Zimmer, the Staff in this case will monitor PG&E's corrective actions to address the timeliness of engineering reviews, and will continue to assess overall performance in the timeliness area through inspections, enforcement actions (if necessary), and the Systematic Assessment of Licensee Performance ("SALP") Program.

The Staff will confirm as part of its routine function that no further improvements are necessary prior to issuance of the construction period recovery license amendment, or prior to operation during the recovered period of operation. Comoare Pacific Gas and Electric Co. (Diablo Canyon Nuclear Power Plant, Units 1 and 2) , ALAB-756,18 NRC 1340, 1354 at n.35 (1983) (leaving a potential enforcement matter to the Staff); Cleveland Electric Illuminatina Co. (Perry Nuclear Power Plant, Units 1 and 2), CLI-86-7, 23 NRC 233, 236 (1986) (" Matters which need to be addressed before licensing can be handled by the Commission and its Staff l outside of the adjudicatory context") . Given the Staff's active l

role in the current issue, there is no justification to reopen the l l

record in this proceeding.  !

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l Furthermore, the NOV itself raises only the single issue of the " timeliness" of PG&E's engineering evaluation of the 1991 j test data. MFP would, in contrast, revisit many of the old matters

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1 identified in IR 93-36; matters long since addressed by PG&E and I l

resolved by the NRC Staff. The NOV simply does not support MFP's arguments that the ASW or CCW systems were "out of compliance" or that this is a " major safety concern" (Motion at 24). The NOV does l not support arguments that the 140 inch differential pressure I setpoint is inadequate (Motion at 13-14), or that PG&E's analysis of ASW system operability is " grossly deficient" (Motion at 16).U' The NOV also does not support the argument that "PG&E's response to Generic Letter 89-13 also misrepresented the facts ..., " or that D' PG&E addressed these unsupported assertions in some detail in its March 7, 1994 response to MFP's original motion (ggg pages 16-17). There is no need to repeat or even reach these substantive arguments here.

such " misrepresentations raise questions about the adequacy and integrity of PG&E's entire maintenance program" (Motion at 24-25).

None of these matters were cited as violations, Severity Level III or otherwise.H' With no proof to support its Motion apart from the NOV, the Motion sinks or swims with the scope of the NOV. Here the Motion sinks, and sinks quickly.

Even if, contrary to the intent of 10 C.F.R. S 2.734, the Licensing Board was inclined to consider the issues of IR 93-36 (other than timeliness) in the absence of new evidence from MFP on those issues, the documentary evidence available to the Licensing  !

Board shows that the issues are not significant. As explained in the attached Affidavit, PG&E's evaluations in response to IR 93-3G conclusively establish:

• The current maintenance program, including the continuous chlorination implemented in 1992, is comprehensive and effective, and assures l the continued operability of the ASW system; i e Both IR 93-36 and PG&E's evaluations in response were primarily directed to certain past conditions at DCPP rather than to ASW or M' MFP's inference -- apparently based on IR 93-36 -- that there was some " intentional deception" in PG&E's response to GL 89-13 is inflammatory and untrue. F_eg e Motion at 24-25. The NRC Staff never alleged intentional errors in PG&E's submittals.

Moreover, the facts germane to these issues were amply explained in PG&E's March 7, 1994 response to the original motion (at pages 13-15, 19-20). And the NRC Staff, in the enforcement action now relied upon by MFP, dropped

" completeness and accuracy" issues. MFP's assertions are flagrantly unsupported.

4 CCW heat exchanger performance since the 1992 implementation of continuous chlorination; and e All of the various " Unresolved" or " Followup" items in IR 93-36, now relied upon by MFP as indicators of "significant" issues, have been addressed by PG&E and closed out satisfactorily by the NRC Staff.

In its March 14, 1994 response to MFP's original motion, the NRC Staff included an " Affidavit of Paul P. Narbut in Support of NRC Staf f Response to San Luis Obispo Mothers for Peace's Motion to Reopen the Record" ("Narbut Affidavit") . Mr. Narbut, the author of IR 93-36 and a Staff witness in this proceeding, also stated that "[t]he NRC does not have any concerns for the current operability of the ASW system at Diablo Canyon." Narbut Affidavit at 1 6. MFP offers no contrary evidence. When the entire history of this matter is considered, including the NRC Staff's disposition of the issues discussed in IR 93-36, it is clear that reopening the record of this proceeding is not justified.M' The Appeal Board has held that, to justify reopening the record, "there must be indication in the 'new evidence' that the decision on the existing record would permit the use of unsafe equipment or create some other situation fraught with danger to the public that merits immediate attention." P_acific Gas and Electric Company (Diablo D' obviously, to the extent MFP would discute the Staff's resolution of IR 93-36 issues that did not result in enforcement, reopening cannot be justified absent a showing from MFP of an independent evidentiary basis on which to dispute the Staff (and PG&E) . MFP offers no such evidence.

l Canyon Nuclear Power Plant, Units 1 and 2), ALAB-598, 11 NRC 876, 887 (1980). The evidence here shows precisely the opposite.

D. MFP's " Evidence" Would Not Lead to a Different Result in this Proceedina Under 10 C.F.R. S 2.734 (a) (3) , a motion to reopen must also provide evidence that on its face would be likely to lead to a materially different result in the proceeding. MFP's Motion does not accomplish this task. To the extent MFP's Motion merely cites now-resolved issues from IR 93-36 that it would like to explore, it clearly fails to provide " evidence" that is relevant to and probative of Contention I in this proceeding. With respect to the NOV on PG&E's lack of timeliness in the engineering analysis of the 1991 test results, the Motion offers only a matter that would not be outcome determinative here.

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As PG&E has discussed in prior filings in this l proceeding, Contention I is a orocrammatic maintenance contention.

The standard for reviewing this contention is not error-free, issue-free, or even violation-free operation. The standard is one of " reasonable assurance" that the DCPP maintenance program is i adequate for continued safe operation. The Licensing Board must R properly focus upon whether there has been a " pervasive" program  ;

implementation problem, whether there has been demonstrated any

" fundamental flaw" in an " essential element" of the program, and whether there are any significant uncorrected deficiencies. E.stst

Union Electric Co. (Callaway Plant, Unit 1), ALAB-740, 18 NRC 3 4 3, 346 (1983); Lona Island Lichtina Co. (Shoreham Nuclear Power Station, Unit 1), ALAB-903, 28 NRC 499, 506-7 (1988).8 A motion to reopen must be evaluated in terms of this pertinent inquiry. To constitute a significant safety issue that would affect the outcome of this proceeding, the motion must present evidence establishing a pervasive breakdown or an uncorrected fundamental flaw in the maintenance program. See Pacific Gas and Electric Co. (Diablo Canyon Nuclear Power Plant, Units 1 and 2), ALAB-756, 18 NRC 1340, 1344-45 (1983). MPP has not met this standard.E' PG&E has already presented in this proceeding ample, unrebutted, evidence of the programmatic effectiveness of the maintenance and surveillance programs at DCPP. See, e.g. , Proposed Findings M50-M94; Reply Findings R4-R17. The NOV that is the entire basis for MFP's Motion focuses only on the timeliness of an enaineerina evaluation. The issue raised is an engineering issue -- not a maintenance issue. See, e.a., Narbut Affidavit at 5 6.g. Furthermore, even if the NOV were construed as a F S_q_q also " Pacific Gas and Electric Company's Proposed Findings of Fact and Conclusions of Law in the Form of an Initial Decision," dated October 8, 1993, at 3-10 (" Proposed Findings"); " Pacific Gas and Electric Company's Reply Findings of Fact and Conclusions of Law," dated December 30, 1993, at 3-5 (" Reply Findings").

E' Compare Pacific Gas and Electric Co. (Diablo Canyon Nuclear Power Plant, Units 1 and 2), ALAB-775, 19 NRC 1361, 1367 (1984) (denying a motion to reopen because the motion established neither uncorrected errors nor a pervnsive breakdown of the quality assurance program).

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maintenance issue, it is an issue relevant only to the operability of the CCW heat exchangers for certain limited periods prior to  ;

l PG&E's implementation of continuous chlorination. There is no l evidence, in an inspection report or otherwise, raising an issue l regarding the operability of the heat exchangers since that time.  ;

1 Thus, theris is no evidence of any ongoing " fundamental flaw" in the !

DCPP maintenance programs. Affidavit at 1 15, 19-20.H' Even l

issues regarding past operability of the service water systems, j involving periods before implementation of continuous chlorination, have been thoroughly evaluated. PG&E has demonstrated that there would have been no adverse impacts on public health and safety had l 1

an accident occurred. ld.

d at 1 20.H' Therefore, even though PG&E takes this matter seriously and has responded to the NOV, this matter cannot affect the outcome of this proceeding.

I Furthermore, the record in this proceeding on PG&E's 1

timeliness in identifying and resolving maintenance issues is very H' It is important to recognize again that the NOV itself does not cite any ongoing operability issue. Furthermore, the issue of potentially inadequate design control flagged in IR 94-08 did not result in enforcement.

E' This evaluation is addressed in detail in Attachment 4, at '

pages 11-13. The evaluation addresses two biofouling bounding periods since operation began at DCPP and orior to implementation of continuous chlorination (in 1990 and at certain times from 1986 to 1988). Even for these periods, PG&E's evaluation shows that public health and safety would not have been adversely affected by ASW system conditions.

This further underscores the lack of " significance" of these issues for this proceeding. MFP seems to attack this evaluation and this conclusion, but again lacks any competent testimony on which to base such an attack.

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clear. The witnesses have given an overall perspective, concluding that PG&E's performance with respect to timeliness in the 1

maintenance and surveillance area has been good. See, e.g., NRC Staff Direct Testimony at 12-13 (Narbut, Miller); see also Reply Findings R28-R34. And even more directly, the NRC Staff inspector that first identified the timeliness issue cited in the NOV has testified that the issue does not change his overall impression of PG&E's performance. Mr. Narbut stated:

Although the report [IR 93-36] identified several issues that may prove to be violations, the NRC Staf f's testimony given at the hearing also discussed several examples where PG&E's performance was not exemplary in maintenance and surveillance areas. The occurrence of problems was included in our overall assessment of their performance at the time of our testimony. It was never our expectation that the PG&E staff would never again have problems in the maintenance and surveillance areas. It is my personal opinion ,

that the inspection report examples will result as negative examples of the performance of engineering but that the overall adequacy of the maintenance and surveillance programs will not be significantly affected by these examples.

Narbut Affidavit at 1 6.d. Given this affidavit, the unrebutted i documentary evidence, and the lack of any contrary testimony from MFP, the conclusion is inescapable that the NOV will not change the outcome of Contention I.

In its Motion, MFP also recites one-by-one some of the other " patterns" of maintenance problems at DCPP it has alleged in its proposed findings of fact. S_ee q Motion at 27-32. MFP invokes the alleged " pattern" of "unreliability of safety systems," of

" inadequate" testing, and of a " lack of communication." However, there is no testimony -- only the assertions of counsel -- to link the purported issues to the purported " patterns." Moreover, PG&E has already addressed these so-called " patterns" and shown that they are rebutted by the overwhelming evidence of record. sig Reply Findings R11, R18-R21, RS3-R58, R62-R66, R69-R74. Now, even assuming that the NOV could somehow be related to maintenance, and then assuming it could be linked to the alleged (and hypothetical)

" patterns," the NOV would not lead to a different result in this proceeding. Another isolated, historical experience, that has been addressed to the satisfaction of the Staff, does not constitute a

" pervasive" failure to implement a maintenance program.

The Licensing Board must not lose sight of the fact that this is a construction period ("CP") recovery proceeding. Similar license amendments have been issued by the NRC to numerous licensees largely as an administrative matter. Operation of a plant without enforcement actions is not and has not been the standard for issuing such amendments. Comoare Tr. 2275 (Peterson)

(testifying that incident-free operation and a SALP 1 rating in maintenance are not necessary to support a CP recovery amendment).

Indeed, the NRC Staff has issued construction period recovery amendments to plants that have received enforcement actions during e

the time the amendment application was pending.N Against this standard, the current NOV cannot change the outcome of this proceeding.

MFP's theory in this case has always been one of listing isolated incidents and counting beans in jars. At most, the timeliness issue raised by the NOV constitutes one more bean in one specific jar. However, one more bean does not make MFP's case on this point. Even a Severity Level III NOV cannot lead to a

" materially different result," given the sheer weight of the evidence already admitted in this proceeding. The operational performance of the plant alone belies MFP's theory of a " pattern" or a " pervasive" breakdown of the maintenance program. See Proposed Findings M50-M56. The Severity Level III NOV itself also includes very favorable findings regarding PG&E's " history of F The NRC Staff has issued construction period recovery amendments to plants that have received enforcement actions during the time the amendment application was pending. For example, EA-91-045 was issued May 31, 1991, to Carolina Power & Light Company (Severity Level III violation with an

$87,500 civil penalty) for maintenance-related violations at the Brunswick plant. The Brunswick CP recapture license amendment was issued on September 12, 1991. Similarly, EA-93-055 was issued May 15, 1993, to GPU Nuclear (Severity Level III violation with a $50,000 civil penalty) for operations-related violations at the Oyster Creek plant. The Oyster Creek recapture license amendment was issued on April 13, 1993. The inspection report and enforcement conference pre-dated issuance of the CP recapture amendment.

Finally, EA-92-134 was issued September 24, 1992, to New York Power Authority (Severity Level III violation with a $100,000 civil penalty) for service water system problems at Indian Point Unit 3. The inspection was conducted in May to July 1992, and the CP recapture amendment was issued in July 1992.

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superior performance" and the " comprehensive corrective actions" l taken. NOV, cover letter at 3. And, while MFP relies on the NRC Staff for the basis for its Motion, the NRC Staff witnesses have concluded that PG&E's maintenance program overall is superior.

Tr. 2214-15 (Miller, Narbut) ; Tr. 2220 (Miller). The NRC Staff has ,

i also placed prior violations in the overall context through its l SALP program assessments and "Best Plants" determinations. See l

Proposed Findings M57-M67. More recently, even as the NRC Staff l l

considered issuing the NOV, DCPP was named yet again to the NRC's "Best Plants" List on June 21, 1994.U' E. MFP's Motion Lacks the Necessary Affidavit As discussed above, a motion to reopen is reauired to include affidavits from " competent individuals with knowledge of the facts alleged, or by experts in the disciplines appropriate to the issues raised." 10 C.F.R. S 2.734(b). MFP's attempt to fulfill this requirement is grossly insufficient. A " declaration" I of counsel asserting no more than that counsel read an NOV and related documents is not at all what the Commission requires to support reopening the record. Counsel in the present case possesses no technical expertise, has no independent knowledge of the f acts and issues addressed in the inspection report, and is not an expert in any of the relevant disciplines. Compare 10 C.F.R.

S 2.734(b). The characterizations of counsel regarding the various D' NRC Letter, J..M. Taylor to R. A. Clarke, dated June 21, 1994.

A copy is included as Attachment 7 hereto.

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issues raised in the NOV and inspection reports are not evidence and do not establish the " significance" of those issues.E' l

l This requirement is more than the trivial procedural l matter MFP treats it as. The Commission's requirement for some .

I contribution of meaningful, independent expertise is an essential  ;

l part of the " heavy burden" inherent in the reopening standard adopted in 1986.U' There are legitimate interests involved in l bringing litigation to a close and in eliminating the expense of pointless litigation. Further evidence and hearings can be I justified only where the movant offers a competent affidavit that )

demonstrates new evidence sufficient to meet the thresholds of I S 2.734. Here MFP relies only on NRC Staff documents, which attests to no more than that the NRC Staff is continuing to perform its ongoing regulatory responsibilities. This proceeding does not l

and should not duplicate the inspection / enforcement process.

Inspection and enforcement findings SLQ Dgt -- absent some unique evidence contributed by MFP -- satisfy 5 2.734. The declaration of counsel is inadequate precisely because it.is not, by definition, U' The " declaration" also raises other problems. By filing the equivalent of an affidavit, counsel seems to be putting herself in the untenable position of being a witness in.this proceeding. .And, by relying solely on the NRC Staff inspector's expertise, counsel must also presumably accept the NRC Staff's expertise in closing out those issues in the enforcement context.

D' S_q.e 51 Fed. Reg. 19535, 19537 at col. 1-2 (1986).

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a competent affidavit providing significant new information unknown to the Staff.E' IV. CONCLUSION MFP has not met the heavy burdens established by 10 C.F.R. S 2.734. MFP has provided no technical basis on which to conclude that the NOV issued on July 14, 1994 involves an uncorrected flaw in the DCPP maintenance program or indicates a pervasive program implementation problem. In fact, the very fact that the NOV was issued ensures just the opposite. Furthermore, the overwhelming evidence already included in the record of this D' Compare Carolina Power & Licht Company (Shearon Harris Nuclear Power Plant, Units 1, 2, 3 and 4), LBP-78-2, 7 NRC 83, 87 (1978) (The Licensing Board, in denying a motion to reopen, specifically observed that, based on the intervenor's previous cross-examination of witnesses, rebuttal testimony, and proposed findings, the probable result of reopening the record would be "more evidence of the same nature and needlessly cumulative"). l I

proceeding demonstrates that the NOV would not change the outcome of the proceeding. Accordingly, MFP's Motion should be denied.

Respectfully submitted, David A. Repka DW.

i N WINSTON & STRAWN 1400 L Street, N.W.

Washington, DC 20005-3502 (202) 371-5726 Christopher J. Warner Richard F. Locke PACIFIC GAS AND ELECTRIC COMPANY 77 Beale Street San Francisco, CA 94106 Attorneys for Pacific Gas and i Electric Company Dated in Washington, DC this 23rd day of August, 1994  ;

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00CKDED UNITED STATES OF AMERICA UbbPC NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of: OffiCL C: U ~~ I@

) 00CKEIliG L RVCf

) Docket Nos. 50-275-0EA.N 7 Pacific Gas and Electric Company ) 50-323-OLA

) (Construction Period (Diablo Canyon Power ) Recapture)

Plant, Units 1 and 2) )

)

CERTIFICATE OF SERVICE I hereby certify that copies of " PACIFIC GAS AND ELECTRIC COMPANY'S OPPOSITION TO SAN LUIS OBISPO MOTHERS FOR PEACE RENEWED MOTION TO REOPEN THE RECORD" in the above-captioned proceeding have been served on the following by deposit in the United States mail, first class, or, as indicated by an asterisk (*), by deposit for Federal Express overnight delivery, this 23rd day of August, 1994.

l Charles Bechhoefer, Chairman

• Frederick J. Shon*

Administrative Judge Administrative Judge Atomic Safety and Licensing Board Atomic Safety and Licensing Board U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Washington, DC 20555 Washington, DC 20555 j I

Jerry R. Kline* Office of Commission Appellate Administrative Judge Adjudication ,

Atomic Safety and Licensing Board U.S. Nuclear Regulatory Commission i U.S. Nuclear Regulatory Commission Washington, DC 20555 Washington, DC 20555 l l

Office of the Secretary U.S. Nuclear Regulatory Commission Ann P. Hodgdon, Esq.*

Washington, DC 20555 Office of the General Counsel Attn: Docketing and Service U.S. Nuclear Regulatory Commission Section Washington, DC 20555 (original + two copies)

Peter Arth, Jr.

Adjudicatory File Edward W. O'Neill l Atomic Safety and Licensing Peter G. Fairchild l Board Panel California Public Utilities U.S. Nuclear Regulatory Commission Commission Washington, DC 20555 505 Van Ness Avenue l San Francisco, CA 94102 {

_. - - - .. . .~ - .- . - . . . - . - - .

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Nancy Culver, President Mr. Gregory Minor Board of Directors MHB Technical Associates San Luis Obispo Mothers for Peace 1723 Hamilton Ave., Suite K P.O. Box 164 San Jose, CA 95125 .

Pismo Beach, CA 93448 l

I Truman Burns Christopher J. Warner, Esq.* i California Public Utilities Richard F. Locke, Esq.

Commission Pacific Gas & Electric Company 505 Van Ness, Rm. 4103 77 Beale Street San Francisco, CA 94102 San Francisco, CA 94106 Robert R. Wellington, Esq. Jill ZamEk  :

Diablo Canyon Independent Safety 1123 Flora Road "

Committee Arroyo Grande, CA 93420  ;

857 Cass Street, Suite D '

Monterey, CA 93940 Robert Kinosian Diane Curran * '

California Public Utilities c/o IEER Commission 6935 Laurel Avenue, Suite 204 505 Van Ness, Rm. 4102 Takoma Park, MD 20912 San Francisco, CA 94102 1

l 1 L David A. Repka \

Counsel for Pacific Gas and Electric Company 4

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ATTACHMENT 1

August 22, 1994 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of: )

) Docket Nos. 50-275-OLA Pacific Gas and Electric Company ) 50-323-OLA

) (Construction Period (Diablo Canyon Nuclear Power ) Recovery)

Plant, Units 1 and 2) )

)

AFFIDAVIT OF MICHAEL J. ANGUS I, Michael J. Angus, being duly sworn, hereby state as follows:

1. I am employed by Pacific Gas and Electric Company ("PG&E") as Manager, Nuclear Engineering Services. In this position I am responsible for overall management of PG&E's engineering support and design engineering activities relating to the Diablo Canyon Nuclear Power Plant ("DCPP").

2. My business address and phone number are:

333 Market Street, Room A1411 San Francisco, CA 94105 l

l (415) 972-5497 l

3. My management responsibilities include engineering issues related to operability of the Auxiliary Saltwater ("ASW")

system and the Component Cooling Water ("CCW") heat exchangers at DCPP. I also have been responsible for engineecing l analyses related to PG&E's continuing programs to address and l mitigate the potential biofouling of service water systems.

4. I have had overall managerial responsibility for developing ,

and reviewing PG&E's evaluation and response to the issues i raised in NRC Inspection Report No. ("IR") 93-36, dated 1 January 12, 1994; NRC IR 94-08, dated March 16, 1994; and the NRC Notice of Violation, Enforcement Action 94-056, dated July 14, 1994. PG&E's evaluation and response to these NRC documents is contained in the following documents:

• PG&E Letter DCL-94-174, " Reply to Notice of Violation in NRC Enforcement Action 94-056," dated August 5, 1994 (Attachment 2);

• PG&E Letter DCL-94-037, " Auxiliary Saltwater System Operability," dated February 15, 1994 (Attachment 3);

• PG&E Letter DCL-94-04 9, " Licensee Event Report 1-93-012-01," dated March 8, 1994 (Attachment 4); and PG&E Letter DCL 94-120, " Licensee Event Report 1-93-012-02," dated May 27, 1994 (Attachment 5).

These PG&E letters respond to the various issues raised by the NRC Staff and referenced in the San Luis Obispo Mothers for Peace Renewed Motion to Reopen the Record, dated August 8, j 1994.

Notice of Violation and Closecuts of Inspection Issues i

5. With the exception of one NRC Notice of Violation, all of the  !

NRC inspection issues cited in the Renewed Motion to Reopen l the Record have been resolved or closed out without enforcement. The Notice of Violation, dated July 14, 1994, cited a Severity Level III violation of 10 C.F.R. Part 50, Appendix B, Criterion XVI, related to the timeliness of corrective actions by PG&E's engineering staff in assessing an issue that arose as a result of tests performed in 1991 to '

determine whether Unit 1 CCW heat exchanger 1-2 had, at that time, the ability to remove the design basis heat load. The 1991 tests and the issue are discussed below; the Notice of i violation, however, dealt only with the untimely review of the  ;

issue caused by poor engineering response. The cover letter I accompanying the Notice of Violation specifically stated that no violations were warranted for the two other potential i violations related to the heat exchanger testing that had been I identified in NRC IR 94-08, dated March 16, 1994. I

6. The cover letter accompanying the Notice of Violation stated that no civil penalty was being imposed for the timeliness violation, because the civil penalty had been mitigated by PG&E's " comprehensive corrective actions, including additional ASW system testing, increased system cleaning frequency, and a commitment to review containment heat removal systems to assure that they meet their design bases, and commitments for improved procedures for defining test acceptance criteria and/or timely resolution of [ Quality Assurance) findings." Notice of Violation, cover letter at 3.

7. PG&E's Reply to the Notice of Violation, dated August 5, 1994 (Attachment 2), demonstrated that PG&E has taken comprehensive corrective actions to resolve the concerns raised by the Notice of Violation and by the previous NRC inspection reports on which the NOV was based. See Attachment 2, Enclosure at 2-

3. These corrective actions specifically include administrative requirements to enhance the timeliness of engineering and other reviews potentially affecting j operability. & at 3. PG&E's Reply to the Notice of '

Violation also reconfirmed that the ASW system is fully operable and capable of meeting its design basis. &

8. The NRC Staff has reviewed PG&E's Reply to the Notice of Violation. In a letter dated August 10, 1994 (Attachment 6),

the Staff stated that it found PG&E's reply " responsive to the concerns raised in our Notice of Violation." The NRC Staff stated that it would review implementation of PG&E's I corrective actions in a future inspection.

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9. With the exception of the one Notice of Violation specifically ,

addressed by Attachments 2 and 6, the combination of the NRC's 1 previous IR 94-08, and the July 14, 1994 letter transmitting the Notice of Violation, closed out all other inspector i follow-up and unresolved items previously identified in IR 93- 1

36. Egg NRC IR 94-08, Inspection Summary at 2; Notice of Violation (Enforcement Action 94-056), cover letter at 1.

Many of those closed issues are now referenced in the Renewed Motion to Reopen the Record. PG&E's comprehensive evaluations of those issues are summarized in Attachments 3, 4, and 5.

Biofoulina Issues

10. The ASW system is designed to remove the heat generated from normal and accident conditions at DCPP and transfer the heat i to the ultimate heat sink (the Pacific Ocean) . The ASW system l specifically provides cooling from the ultimate heat sink to  !

the CCW system. The CCW system removes waste ~ heat from primary plant equipment during normal plant operation, plant cooldown, and following an accident. The ASW system has been designed to remove sufficient heat from the CCW system to maintain the temperature of the CCW system within its design limits under normal, transient, and accident conditions.

11. The ASW system has two pumps capable of pumping seawater to the tube side of either of two CCW heat exchangers. In addition, either heat exchanger can be supplied by an ASW pump from the other DCPP unit via a cross-tie. Consistent with the NRC's policies pertaining to allowed outage times for maintenance, the DCPP Technical Specifications (3/4.7.4) permit either heat exchanger to be taken out of service for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for maintenance or other reasons.

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12. The CCW pumps route component cooling water to the shell side of the two CCW heat exchangers. Heat transferred to the CCW systems is then transferred to the ASW system through the two CCW heat exchangers. The operability of the ASW system is a function of its heat transfer capacity. Quite obviously, the heat transfer capacity required for accident conditions is much greater than for normal operations, and all of the issues here relate to operability for design basis accident conditions rather than normal operations.

13. The potential for biofouling problems in service water systems was described in NRC Generic Letter ("GL") 89-13, " Service Water System Problems Affecting Safety-Related Equipment,"

issued in July 1989. As GL 89-13 explained, this potential problem is not unique to particular plants, but was a generic issue in the industry and the reason the NRC issued the GL on the subject. PG&E responded to GL 89-13 by letters dated January 26, 1990, and November 26, 1991, with specific commitments to address the recommendations of the GL.

14. As part of PG&E's response to GL 89-13, an ASW system monitoring program (involving flow testing, trending, inspection, and maintenance) was implemented to ensure that the system would retain its design basis capability. PG&E also performed in 1991, as a supplement to the monitoring program, one-time heat exchanger performance testing on the CCW heat exchangers.

15. In 1992, PG&E upgraded its chlorination system at DCPP to a continuous chlorination program that is very effective in controlling biofouling of the ASW system and CCW heat l exchangers. The continuous chlorination has significantly l reduced the frequency of CCW heat exchanger outages for l cleaning.  ;

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1991 Heat Exchancer Testina

16. The performance test conducted in February 1991 on one of the )

CCW heat exchangers, the CCW 1-2 heat exchanger, showed a heat exchange ratio of 0.987. PG&E's engineering review of the test results at the time was based on its engineering judgment of the collective results for all four CCW heat exchangers, as well as the similar design of the heat exchangers and the perceived relative uncertainties of the test methodology.

PG&E concluded that CCW heat exchanger 1-2 could meet its design basis. SES Attachment 3, Enclosure 1 at 7-8 and Enclosure 3 at 3-4; Attachment 4 at 6.

17. In response to NRC concerns raised in December 1993 concerning the test results, PG&E reevaluated the test results and concluded that CCW heat exchanger 1-2 did not meet the design 8 1 (nameplate) heat transfer capability at the time of the test in February 1991, using the particular test computer model used at that time. However, PG&E's reevaluation also concluded that, in retrospect, the performance of the CCW 1-2 heat exchanger at the time of the test in February 1991, was in fact 101 percent of the design nameplate rating with a 95 percent confidence level, using a second, validated GL 89-13 test model. S_qn Attachment 3, Enclosure 1 at 8 and Enclosure 3 at 4; Attachment 4 at 7.

18. Additional testing on the Unit 1 CCW heat exchangers was completed on April 26, 1994. These tests confirmed that the heat exchangers have significant margin above design basis and that both Unit 1 heat exchangers are performing significantly better than the 1991 GL 89-13 test results. The results of the April 1994 tests were as follows:

COMPONENT HEAT EXCHANGE RATIO CCW HX 1-1 1.176 CCW HX 1-2 1.160 These test results are documented in the revised Licensee Event Report issued on May 27, 1994. e S_e_g Attachment 5 at 7.

19. In addition, PG&E Letter No. DCL-94-037, dated February 15, 1994 (Attachment 3), showed that PG&E's maintenance program for the ASW system at Diablo Canyon is comprehensive and effective, and assures that the ASW system is operable and capable of meeting its design basis requirements. See Attachment 3, cover letter and Enclosure 1.

Conclusion

20. The issues raised by the NRC in IR 93-36 regarding operability of the ASW system and CCW heat exchangers relate to past --

not current --

conditions. Furthermore, the safety evaluations in the attachments accompanying this Affidavit demonstrate that the public health and safety was not adversely affected by the potential for degraded ASW system performance due to biofouling prior to the 1992 implementation of continuous chlorination. Sfqn, e . cr . , Attachment 3, Enclosure 2; Attachment 4 at 11-13.

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21. The information contained in this affidavit is true and correct to the best of my knowledge and belief.

rd" CHAEL ' KN S Subscribed and sworn to before me t s4J7 , day of August, 1994 l

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M SU /

Notary Public [/

N Msl 20 l995 My Commission Expires me====semum xemoun-OFFICIAL SEAL ROSA W. SCHOENING 9 NOTARY PUBUC-CAUFORNIA Isensessessesseousase& COUNT CITY My Commission Expires March 20,1995l essassessessessessassessansass eces 5 l

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ATTACHMENT 2

i 222512 Pacific Gas and Electric Company 77 BWe Ster h:m 1451 Te;: p,e ax;er F0 B:4770330 sem:r v,:e N::rt at I GeTa'f.v.a;r San Fran::s:: CA 94177 415/973 4534 NJ:.za P:c.r Geerr.:n Fan 415/973 2313

, RECEIVED August 5,1994 AUG 111994 PG&E Letter DCL-94-174 CHRISTOPHER J. WARNER q.g,h U.S. Nuclear Regulatory Commission id U r; ATTN: Document Control Desk Washington, D.C. 20555 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Repiv to Notice of Violation in NRC Enforcement Action 94-056 (NRC Inspection Report Nos. 50-275/94-08 and 50-323/94-08)

Gentlemen:

NRC Enforcement Action 94-056, dated July 14,1994, contained a Notice of Violation that cited one Severity Level 111 violation. The violation involved the failure of PG&E's engineering staff to promptly identify and correct issues that arose as a result of tests performed in 1991 to determine whether the Component Cooling Water Heat Exchanger 1-2 had the ability to remove the design basis heat load. The root cause of the violation was determined to be inadequate attention to engineering practices that should have ensured clear definition of test acceptance criteria for the heat exchanger testing prior to the test being performed and a failure to comprehensively resolve the negative test results in a timely manner. Specific concern was expressed about PG&E's failure to take advantage of several opportunities, particularly our own Quality Assurance organization's self-identification of the deficiency in mid-1993, to thoroughly resolve the issue prior to the NRC's inspection in late 1993.

As discussed in DCL-94-037, dated February 15,1994, and DCL-94-049, dated March 8,1994, PG&E conducted a comprehensive evaluation of these concerns and has taken extensive corrective actions to address them. The commitments made in these previous responses constitute the corrective actions we have taken or intend to take. PG&E believes that its previous Generic Letter (GL) 89-13 program, combined with these additional corrective actions, provide assurance that the ASW system is fully operable and capable of meeting its design basis. Recent testing and inspection activitiesi confirm the effectivaness of these actions.

August 5,1994 PG&E Letter DCL-94-174

• 222512 PG&E agrees with the violation. PG&E's response to the Notice of Violation is

- enclosed. .

Sincerely, W Su m l Gregory M. Rueger Subscribed and sworn to before me Attorneys for Pacific Gas and this 5th day of August 1994 Electric Company Howard V. Golub Christ pher J. Warner

/ 1; Y f ! ;- .i j M

!, Notary Public Christophe(J. Wper cc: L. J. Callan Mary H. Miller m_______~_ ______

Kenneth E. Perkins ~ ' ~ ~ sJ si-~sd ~~~ ^'s BlANCA E. ZELNIK I Sheri R. Peterson Diablo Distribution Y p7[$ $0" , $

My emwan wm f.g a q

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Enclosure DCO-94-EN-N022 i

6552S/TLG/2246

PG&E Letter DCL-94-174 ENCLOSURE 222512 REPLY TO NOTICE OF VIOLATION IN NRC ENFORCEMENT ACTION 94-056 On July 14,1994, as part of NRC Inspection Report Nos. 50-275/94-08 and 50-23/94-08, NRC Region IV issued Enforcement Action 94-056 that contained a Notice of Violation citing one Severity Level til violation for Diablo Canyon Power Plant Unit 1. The statement of violation and PG&E's response follow.

STATEMENT OF VIOLATION

• During an NRC inspection conducted on February 28, March 1, and March 8,1994, a violation of NRC requirements was identified. In accordance with the ' General Statement of Policy and Procedure for NRC Enforcement Actions,' 10 CFR Part 2, Appendix C, the particular violation is set forth below:

10 CFR Part 50, Appendix B, Criterion XVI, ' Corrective Action,' states, in part, that measures shall be established to assure that conditions adverse to quality, such as failures and nonconformances are promptly identified and corrected.

In the case of significant conditions adverse to quality, the measures shall assure that the cause of the condition is determined and corrective action taken to preclude repetition.

. Contrary to the above, during a test conducted on February 2,1991, Component Cooling Water (CCW) Heat Exchanger 1-2 failed to demonstrate the ability to remove the design basis heat load, as documented in Field Test Report 420DC-91.1156, and the measures established by the licensee did not assure that this significant condition adverse to quality was promptly corrected or that the cause of the condition was determined. Despite this condition being recogni2.ed in the above referenced Field Test Report dated November 22,1991,in Action Request No. A0306715 dated May 10,1993, and in Quality Assurance report SQA-93-0031 dated July 28,1993, the licensee did not take prompt action to correct this condition, to assess the impact of fouling on heat exchanger performance or to determine the significance of this condition with respect to the operability of the Auxiliary Saltwater System (ASW).

This is a Severity Level 111 violation (Supplement 1)."

6552S 222512 REASON FOR THE VIOLATION PG&E agrees that resolution of the original 1991 heat exchanger testing issues and the 1993 Site Quality Assurance (SQA) surveillance findings was not as thorough or comprehensive as PG&E management would expect. In response to the SOA surveillance, PG&E technical organizations continued to conclude that the SQA surveillance issues did not represent current operability n cerns. This was based on engineering judgment that existing programs, described in response to Generic Letter (GL) 89-13, effectively assured current ASW system operability. In addition, a failure by both technical and quality organizations to take adequate ownership for resolution o the concerns contributed to these events.

CORRECTIVE STEPS TAKEN AND RESULTS ACHIEVED

1. A full and thorough engineering analysis and test review of heat exchanger operability has been performed (confirmatory testing on Unit 2 awaits the Unit 2  :

sixth refueling outage in October of 1994) to resolve all issues raised and '

demonstrate ASW system operability.

2. PG&E has established an Integrated Problem Response Team (IPRT) whose purpose is to perform an integrated review of the ultimate heat sink systems, i including the CCW heat exchangers, and to recommend enhancements.

Membership of the team is multi-departmentalincluding members from operations, quality services, regulatory services, engineering, and Westinghouse.

3. Design engineering, system engineering and licensing personnel involved with the GL 89-13 testing, analysis, and submittal preparation were counseled on the l thoroughness that must be applied when engineering judgment is used to justify l

acceptance of test deviations. l

4. A case study describing the situation, communications, corrective actions, and management's expectations on the events surrounding the ASW heat exchanger testing was conducted with appropriate NPG personnel. The Directors of System Engineering, Mechanical Engineering, and Site Quality Assurance presented the case study. PG&E believes that by using the Directors to lead the case study, a clear message of expectations on the high standards of thoroughness, clear communication, and delineation of responsibilities were fully reemphasized to the technical staff.

5. Procedure AD1.lD1, " Format, Content and Style of Procedures, was revised subsequent to the performance of the GL 89-13 heat exchanger testing to . squi that comprehensive acceptance criteria be documented for special tests.

6. Equipment Control Guideline 17.2," Auxiliary Saltwater Continuous Chlorination System," was issued to provide administrative controls on the ASW chlorination system.

6552S 222512

7. In addition to inspections performed when the CCW heat exchanger differential

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pressure (dp) limits are reached, recurring work orders have been created to clean the dp lines for each CCW heat exchanger every six months.

8. Performance testing was completed on the Unit 1 CCW heat exchangers that ,

verified the adequacy of the dp setpoint and the current maintenance program.

CORRECTIVE STEPS THAT WILL BE TAKEN TO AVOID FURTHER VIOLATIONS

1. Procedure AD13.lD1,' Conduct of Plant and Equipment Tests," will be revised to require that deviations from acceptance criteria be documented and justified i prior to acceptance of the deviation.

l The IPRT is scheduled to complete its review by December 31,1994. After l 2.

completion of the IPRT, additional design basis information will be added, as l' appropriate, to the relevant Design Criteria Memoran'.a.

3. Administrative procedures will be revised to assure timely evaluation of c:uality organization concerns involving potentially degraded conditions.

4. Upon completion of the Unit 2 heat exchanger performance tests scheduled for the Unit 2 sixth refueling outage, PG&E will reevaluate the CCW heat exenanger dp setpoint.

5. Enhanced ASW flow instrumentation will be installed with local readouts.

DATEWHEN FULL COMPLIANCE WILL BE ACHIEVED i Based on a comprehensive review of the design basis, maintenance programs, and test results for the CCW heat exchangers, PG&E considers this system to be operable and capable of meeting its design basis requirements. Procedure AD13.lD1 will be completed by September 9,1994. The IPRT will complete its review by December 31,1994. Reevaluation of the dp setpoint will be completed by December 31,1994. Installation of enhanced ASW flow instrumentation with local readouts will be completed by June 30,1995.

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Pa:ific Gas anr1 Electric Company ?? Bea'e Street. Roorn 1451 Gregory M Rueger P0 Box 770000 Senior Vee President and San Francisco. CA 94177 General Manager 415/973-4684 Nuclear Power Generanon Fax 415/973-2313 February 15,1994 PG&E Letter No. DCL-94-037 h U.S. Nuclear Regulatory Commission ATTN: Document Control Desk d Washington, D.C. 20555 Re: Docket No. 50-275, OL-DPR 80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Auxiliary Saltwater System Operability Gentlemen:

NRC Inspection Report Nos. 50-275/93-36 and 50-323/93-36, dated January 12,1994, identified a number of NRC unresolved items and concerns related to the operability of the auxiliary saltwater (ASW) system.

PG&E's comprehensive evaluation of current ASW system operability concludes that the ASW system is operable and capable of meeting its design basis requirements. This is based on the following actions PG&E has taken since issuance of NRC Generic Letter (GL) 89-13 in 1989: (1) The ASW system is continuously chlorinated, which effectively controls biofouling; (2) The component cooling water (CCW) heat exchangers are taken out-of-service and cleaned prior to the differential pressure (dp) reaching 140 inches, a level which PG&E's engineering analysis and empirical experience indicates is acceptable to assure the design basis capability of the ASW system; (3) PG&E has implemented a comprehensive maintenance, inspection and monitoring program in compliance I

with GL 89-13; and (4) PG&E's reanalysis of the results of baseline performance tests of CCW heat exchangers performed in 1991 shows that all four heat exchangers meet design basis requirements. The 1991 test result for the CCW 1-2 heat exchanger was attributable to its microfouled condition at the time of the test.

In addition to these actions, PG&E recently performed testing of the ASW pump flow through the CCW heat exchangers to provide additional information on current ASW flow rates, pump runout, and dp. This additionalinformation confirms the effectiveness of PG&E's GL 89-13 actions and the current operability of the ASW system.

Although PG&E has concluded that the ASW system has been operable at all times since implementation of its GL 89-13 program during 1R4 and 2R4, PG&E also is conducting an analysis of ASW system operating conditions from startup

?G&E Letter No. DCL-94-037 February 15,1994 to the implementation date of GL 89-13 to assess potential past operability issues. PG&E's preliminary review indicates that the ASW system has been operable for all periods prior to PG&E's implementation of GL 89-13, with two possible exceptions. The first may have occurred in 1990 when an unusual period of potential microfouling coincided with the chlorination system being out of service for piping replacement. This coincidence of events created the potential for excessive microfouling of the Unit 1 CCW 1-2 heat exchanger.

The second exception may have occurred at certain times in 1986-1988 when ASW flows may have been lower than required to support the dp setpoint used to indicate the need for heat exchanger cleaning. However, in both cases, PG&E's preliminary safety evaluation concluded that the ASW system, together with credible operator action, would have ensured that the public health and safety were not adversely affected. PG&E will provide a supplement to this letter when the final results of its past operability analysis are complete.

The NRC Inspection Report identified concerns regarding the timeliness of PG&E's corrective actions, and the accuracy and completeness of information provided by PG&E regarding ASW system operability. PG&E agrees that, at the time of the NRC inspection, it had not resolved the ASW system operability issues raised by its quality organization earlier in 1993. In retrospect, as discussed in more detail in Enclosure 3, PG&E did not resolve the quality issues as thoroughly or as quickly as PG&E management would expect.

However, PG&E engineering personnel had responded to the quality issues. At that time, PG&E engineering judgement was that system operability was assured because of the effectiveness of heat exchanger maintenance programs and the design margin believed to exist for the system. As discussed above, PG&E's subsequent evaluation demonstrates that the dp setpoint is acceptable and that the ASW system has been operable since PG&E's implementation of GL 89-13. Therefore, any untimeliness did not adversely affect i the public health or safety.

In regard to the Inspection Report's concerns with the accuracy and completeness of information provided by PG&E in response to GL 89-13, PG&E is committed to the highest levels of accuracy and credibility in the information it provides to the NRC and the public, and takes very seriously any issue raised relating to this commitment. Based on its  !

comprehensive review of relevant documents and information related to this issue, PG&E l believes that its statement regarding the results of heat exchanger performance testing was accurate and complete when considering the guidance in the GL, as well as the previous information PG&E had provided the NRC regarding the limitations and inconclusiveness of i such testing. However, PG&E agrees that its engineering evaluation of the test results  !

should have been more comprehensive. In regard to the status of its ASW piping inspection program, PG&E believes that its statement was accurate and complete. This is because a temporary piping inspection procedure had, in fact, been established. Piping 4 inspections had taken place, a frequency interval of every fourth refueling outage had been set, and conversion of the temporary procedure to a permanent Surveillance Test Procedure was being formally tracked, consistent with PG&E's practices for new surveillance and ,

maintenance programs. l Although present operation, testing, and maintenance practices provide assurance of ASW system operability, PG&E intends to take the following corrective actions. An Integrated l l

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PG&E Letter No. DCL-94-037 3- February 15,1994 Problem Response Team (IPRT) review of the ASW, CCW, and containment heat removal systems will be performed to assure that these systems meet their design bases requirements. Additional functional testing of the CCW heat exchangers will be performed to further verify'the adequacy of maintenance programs and operational controls.

Enhanced ASW flow instrumentation will be provided with local readout. To improve timeliness, PG&E's program for evaluating concerns involving potentially degraded conditions will be strengthened. In addition, engineering personnel will be counseled on the l need for thoroughness and a questioning attitude in analyzing design basis issues that represent a potential challenge to system operability.

PG&E's detailed evaluations are provided in the following enclosures:

• Enclosure 1 - Discussion of ASW system design basis and system operability.

• Enclosure 2 - Preliminary evaluation of past operability of the ASW and CCW systems, i

including safety significance.

• Enclosure 3 - Detailed response with PG&E's corrective actions for the specific concerns, issues, and unresolved items identified in the NRC Inspection Report.

PG&E remains confident that the overall quality of engineering for Diablo Canyon Power Plant (DCPP) remains high and that the concerns identified in the inspection Report are atypical. PG&E's past evaluations of the CCW heat exchangers were based on reasonable engineering judgements at the time. PG&E's maintenance, testing, and inspection programs for the ASW system are comprehensive and assure continued operability of the system. PG&E believes that the corrective actions taken will assure that the concerns raised in the NRC Inspection Report and PG&E's root cause evaluation will be promptly resolved.

Sincerely, f

% AM. m Gregory M. Rueger cc: Mary H. Miller Kenneth E. Perkins Sheri R. Peterson Diablo Distribution Enclosures 6352S/TLG/2237

l PG&E Letter No. DCL-94-037 ENCLOSURE 1 l DISCUSSION OF AUX /UARY SALTWA TER SYSTEM DESIGN BASIS AND SYSTEM OPERABlUTY

SUMMARY

i The following is a discussion of the current operability of the ASW system, its design bases, key parameters affecting operability, and PG&E's maintenance, operational, and testing activities that assure continued operability.

The ASW system is designed to remove the heat generated from normal and accident conditions at Diablo Canyon and transfer the heat to the ultimate heat sink.

The primary design consideration used to accomplish this function is to maintain the CCW system temperature within its allowable limits, while maintaining containment pressure within its design limits during a loss of coolant accident (LOCA) or a main steam line break (MSLB) inside containment.

Several key parameters directly or indirectly affect CCW heat exchanger heat transfer capability. These parameters and the current maintenance, operational, and testing practices that are used to control them, include:

Parameters

• Macrofouling

• Microfouling and scaling

• ASW flow and ocean temperature Monitorino and Testina

• ASW flow and ocean temperature

• Differential pressure

• Inspections and sampling during tube cleaning Maintenance

• Continuous chlorination

• Tube cleaning / scraping /waterjet cleaning As discussed below, these parameters have been evaluated and are considered to be sufficiently controlled by the currerst operational, maintenance, and testing practices at DCPP to assure that the design basis heat removal capacity of the CCW system is 6352S -1

maintained. Therefore, based on PG&E's evaluations, the ASW system is cperable and capable of performing its safety function.

ASW SYSTEM DESIGN HEAT TRANSFER CAPACITY The operability of the ASW system is a function of its heat transfer capacity. The ASW system provides cooling from the ultimate heat sink, the Pacific Ocean, to the CCW system. The CCW system removes waste heat from primary plant equipment during normal plant operation, plant cooldown, and following an accident. The ASW system has been designed to remove sufficient heat from the CCW system to maintain the temperature of the CCW system within its design limits under normal, transient, and accident conditions.

The ASW system has two pumps capable of pumping seawater to the tube side of either of the two CCW heat exchangers. In addition, either heat exchanger can be supplied by an ASW pump from the other unit via a cross-tie. The CCW pumps route component cooling water to the shell side of the two CCW heat exchangers.

The heat transferred to the CCW system is then transferred to the ASW system through the two CCW heat exchangers.

Following a LOCA or an MSLB inside containment, the CCW system is required to provide cooling water to the containment fan cooling units (CFCUs) for containment heat removal, and to the various engineered safeguards features (ESF) pump coolers.

During the recirculation phase of a LOCA, the CCW system also cools the residual heat removal (RHR) heat exchangers. The current design limits on CCW are that the CCW water temperatures must remain at or below 120*F for continuous operation, but may exceed 120 F, up to a maximum of 132'F, for no longer than 20 minutes.

Since January 1989, the Emergency Operating Procedures (EOPs) have included instructions for the control room operators to place the second CCW heat exchanger in service in the event that one of the two trains of ASW pumps is not operating.

Since December 1991, the EOPs have included instructions, upon entry into ,

recirculation, to reduce the number of operating CFCUs to a maximum of three, and l to secure the second RHR pump if two ASW pumps and two CCW heat exchangers l are not operating. These actions assure that the CCW system will operate within its design limits [See Licensee Event Report (LER) 1-84-040 (March 24,1989);

LER 1-91-018 (June 29,1992); Final Safety Analysis Report (FSAR) Update, page 9.2-5; and NRC Safety Evaluation Report, Supplement 16, pages 9-5 to 9-7 (August 1983)].

During normal plant operation, the CCW system is designed to remove heat from the CFCUs, ESF pun.p coolers, and various nonessential heat loads. Only one heat exchanger is normally in service during normal plant operation. In addition, the system is designed to meet single failure criteria. Therefore, the design of each CCW heat exchanger is to remove 100 percent of the design heat load from the CCW  !

system under both normal and accident conditions. i 1

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l The temperature of the CCW system is primarily a function of heat input to the system by the CFCUs (and RHR heat exchangers during recirculation), and heat i removal by the ASW system. The analysis in Westinghouse WCAP 12526, Rev.1, i

" Auxiliary Salt Water and Component Cooling Water Flow and Temperature Study for I Diablo Canyon Units 1 and 2," provides curves establishing the acceptable combinations of ASW flow and ocean temperature such that the CCW system heat i removal requirements are met, assuming that the full surface area of the CCW heat '

exchanger is available and that the CCW heat exchanger is operated at its design i fouling factor of 0.001. The fouling factor establishes a margin that accounts for the degree to which fouling will affect heat transfer, and the fouling factor used in the design is an industry standard.

ORIGINAL DESIGN BASIS AND SUBSEQUENT REVISION IN 1983 The CCW heat exchangers were purchased in December 1969 from the Yuba Heat Transfer Corporation. The heat exchangers were designed for a heat load of 258 x 10' BTU /hr. Subsequent to the original heat exchanger specifications, Section 9.2.7 of the FSAR was issued showing that the peak heat rejection rate required was actually only 252 x 10' BTU /hr.

This maximum heat lead of 252 x 10' BTU /hr, which prior to 1983 served as the basis for the design of the ASW system, assumed three CFCUs in operation (based I upon single failure of an electrical bus). Another accident scenario was investigated in early 1983, based upon a different single failure. This new scenario assumed a i design basis LOCA (doubled-ended cold leg RCS pump suction piping guillotine break) coincident with a single active failure of an ASW pump. In this event, all five CFCUs and all three CCW pumps are assumed to start. This scenario results in a higher rate of heat removal from the containment atmosphere by the CCW system. The heat input into the ASW system during this scenario is 325 x 10 8BTU /hr. The CCW heat exchangers have sufficient heat removal capability to maintain the CCW supply temperature at or below the maximum allowable temperature for cooling of safeguards equipment.

The limiting CCW temperature transient has been analyzed by Westinghouse. This analysis (WCAP-12526, Rev.1) determined, for various scenarios, the required ASW flow rate as a function of ocean water temperature to maintain the CCW temperature within its design basis limit. The results of this analysis were summarized in acceptance curves for various ASW flows and ocean temperatures. This information was incorporated into the monthly Surveillance Test Procedure (STP) M-26, "ASW System Flow Monitoring," acceptance criteria, and includes corrections to the indicated ASW flow (measured at the ASW annubars) for the test conditions.

Conservatisms are applied to the STP M-26 measured flows to account for possible system alignments and ocean conditions, to assure minimum accident flow requirements are met.

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NRC INSPECTION REPORT ISSUES NRC Inspection Report Nos. 50-275/93-36 and 50-323/93-36 identified a significant un' resolved item relating to the basis for the operability of the ASW system with regard to operational limits on macrofouling and microfouling. The following is PG&E's evaluation of each of these operability issues:

BACKGROUND Macrofouling Macrofouling is the blockage of flow through the heat exchanger tubes due to mussels and barnacles in the seawater environment, or due to any potential foreign l materials. Blocked heat exchanger tubes reduce the heat transfer capability of the heat exchanger since the effective surface area is reduced. The percent of tube blockage that is acceptable before the heat transfer capability of the heat exchanger i is inadequate varies according to the ocean temperature, the ASW flow, the degree I of concurrent microfouling, and the type of blockage that occurs (e.g., a fully blocked tube has no heat transfer contribution, but a partially blocked tube with decreased flow around the blockage will continue to provide some heat transfer capability). For the purpose of evaluating both heat transfer and dp, macrofouling is conservatively assumed to block the tube completely, such that its contribution to heat transfer is completely negated. This is accounted for in the heat exchanger modeling by a reduction in the effective tube surface area of the heat exchanger equal to the total surface area of the blocked tubes. However, under actual conditions, macrofouling is unlikely to cause complete tube blockage. j l

Microfouling and Scaling i Microfouling, as referred to in this document, includes both organic and inorganic materials that adhere to the walls of the CCW heat exchanger tubes and, by their presence, degrade heat transfer at the tube surface. Organic components include i bacteria, algae, fungi, and the extracellular byproducts of these organisms (e.g.,

polysaccharides and slime). Inorganic components include silt, scale, and other deposited minerals. The presence of an established organic layer can encourage the adhesion of inorganic materials from the seawater to the tube surface.  !

Scaling is related to the operation of the cathodic protection system. Calcium carbonate can be expected to plate out on the inside surface of the tube near the ends of the tubes. This is the result of the reaction of the saltwater with the cathodic protection system. The cathodic protection is designed to protect a limited area and the further the distance from the cathodic protectior) source, the weaker the electric potential. Therefore, the rate of deposition will be lower the further into the tube from the ends. Based on experience, the deposits due to this phenomenon occur in the last 12 to 18 inches of the tubes and for a few inches beyond the end of the tube inlet inserts.

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The actual heat transfer area of the CCW heat exchanger affected by calcium carbonate deposits is approximately 2 percent of the total area. Based on observations, calcium carbonate deposits occur over a few inches on all the inlet ends of the tubes just beyond the plastic tube inserts. Deposition occurring on the outlet end of the lower section of tubes is thicker than on the intet; this is believed to occur because the inserts on the inlet insulate the tubes from the electrochemical reaction. Since the calcium carbonate deposition is a thin layer and the affected surface area is small, the overall impact on the heat transfer capacity is small. An evaluation has estimated the reduction in the overall heat transfer capability of the heat exchanger to be less than 1.0 percent.

Calcium carbonate deposits, along with other inorganics, can also result in buildup that could result in flow blockage through the tubes, thereby impacting thermal performance. To prevent this from occurring, PG&E has implemented a routine mechanical tube scraping each refueling outage. This interval has been shown to be effective in maintaining the buildup of deposits to less than the inside diameter of the plastic inserts on the inlet of the tubes. Therefore, macrofouling and large debris will become lodged in the inlet end of the tubes and not further down along the tube length due to inorganic depositing. However, regardless of where the flow blockage occurs along the tube length, it will be detected as a contribution to the dp measurement across the heat exchanger.

Historically, microfouling has not been a problem at DCPP because of the :old average ocean temperatures along the central coast of California. However, seasonal ocean vark. ms called upwelling and warm ocean temperatures can affect biological growth ad increase microfouling. During the spring and early summer, the prevailing northwest winds at DCPP provide the driving force that moves the warmer surface ocean layers in an offshore direction. Cold water then wells up from deeper layers to replace the displaced surface water. This water is typically rich in nutrients conducive to microbiological growth, but the water is usually at such a low temperature (45'F to 55"F) that little or no biological microfouling occurs.

However, if the crostal winds decrease, the ambient seawater temperature can rise to a point where the combination of nutrients and warmer temperatures (above approximately 58*F daily average ocean temperature) can allow microfouling to proliferate if accompanied by a lack of adequate biofouling controls. A historical review of the environmental and ASW operating conditions at DCPP indicates that there has been one short period when a combination of these factors created a l

potential for excessive microfouling. This period was July-August 1990, when the batch chlorination system was out-of-service while cast iron piping in the system was being replaced, and the ambient seawater temperature exceeded 58"F following an ocean upwelling period. l Heat Exchanger Differential Pressure Continuous monitoring of the dp across the heat exchanger is an important I diagnostic tool used to assess the heat exchanger condition during operation. l Differential pressure is monitored by taking daily readings, as well as by a dp alarm in the control room. Differential pressure provides an indication of the heat exchanger 6352S 5-

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condition that is qualitatively linked to each heat exchanger's heat transfer capability.

Although the measured dp across the heat exchanger does not provide an all-inclusive indicator of heat exchanger performance, it does give a general indication of the combined effect of macrofouling and heavy scaling. Therefore, the dp measurement, with microfouling under control, is one indicator of overall heat exchanger functionality. Maintenance, surveillance testing, and inspections during cleanings are also other indicators.

EVALUATION OF CURRENT OPERATIONAL LIMITS ON MACROFOULING AND MICROFOULING Continuous Chlorination As the Inspection Report notes, PG&E has implemented a continuous chlorination  ;

program that is very effective and has significantly reduced the frequency of heat i exchanger outages for cleaning. Prior to implementing continuous chlorination in i 1992, various methods had been used at DCPP to control both micro- and macrofouling. Batch chlorination was in use at DCPP from late 1984 to mid 1991, l although a few periods existed during this timeframe when equipment problems or system enhancement modifications precluded the use of chlorination. Both methods of chlorination can control the growth of macrofouling as ws!! as microfouling, although continuous chlorination is a superior method. The control of macrofouling requires higher chlorine concentrations than the control of microfouling; however, DCPP continuously maintains sufficient chlorine in the ASW system to control both types of biofouling in the piping and the heat exchangers.

Since full implementation in 1992, the continuous chlorination system has operated effectively. However, to assure equipment availability for chlorination, Equipment Control Guideline (ECG) 17.2, "ASW Continuous Chlorination System," has been approved to provide administrative controls on the ASW chlorination system. This ECG specifies the length of time that the continuous chlorination system may be out-of-service without compensatory actions to control biofouling, in addition, the ECG includes a periodic surveillance requirement to verify that adequate chlorination is being performed.

2 Heat Exchanger Tube Cleaning, Scraping and Waterjet Cleaning in accordance with Maintenance Procedure MP M-56.16, " Heat Exchanger Tube Cleaning," the heat exchanger tubes are mechanically scraped during each refueling outage (nominally every 18 months). Cleaning of the tubes with a waterjet has been performed periodically in the past during macrofouling cleaning (whenever the dp  ;

reaches its administrative limit), as discussed below.

Maintenance History and Observed Results Without adequate controls during the proper oceanic conditions, microfouling of the tube side of the CCW heat exchanger can be a significant contributor to the reduction in heat exchanger performance. The average amount of microfouling 6352S l

found at the time of cleaning has been as high as 7.9 9 (dry weight) in the tubes .

sampled. This was a peak result during an unusual period of high susceptibility to -

microfouling during which chlorination had been out of service for ~several months.

Following the initiation of continuous chlorination, a m' ore representative figure has been less than 1.0 g (dry weight) per tube. In addition, microscopic analysis of the material removed from the tubes after initiation of continuous chlorination indicates little organic material present (i.e., mostly sediment rather than biofouling). This indicates that the rate of biofouling and its subsequent impact on heat exchanger performance is being effectively controlled by the continuous chlorination program and the regular tube scraping during each outage. When controlled in this manner, microfouling and scaling will not have a significant impact on the heat transfer capability of the heat exchangers.

Historically, the frequency of heat exchanger cleaning prior to the initiation of continuous chlorination had been every four to six weeks. The current cleaning interval with continuous chlorination in service is approximately every six to eight months. The longer cleaning intervals are indicative of the lower rate of macrofouling due to the effectiveness of continuous chlorination.

EVALUATION OF GL 89-13 BASELINE HEAT EXCHANGER TEST RESULTS The performance of the four CCW heat exchangers (the ratio of predicted heat exchanged under accident conditions versus design nameplate heat exchanged) was as follows. These results include the effects of as-tested macrofouling and microfouling including calcification and scaling.

COMPONENT HEAT EXCHANGE RATIO CCW 1-1 HX 1.080 CCW 1-2 HX O.987 CCW 2-1 HX 1.112 CCW 2-2 HX 1.109 The results of the GL 89-13 testing on the CCW 1-2 heat exchanger indicated a heat transfer capability of 98.7 percent of the design value (97.5 percent after accounting for 1.2 percent uncertainty). A review of the 1990-1991 operating and cleaning history indicates that no chlorination was applied to any of the four CCW heat exchangers during the summer 1990 ocean upwelling and warming period, due to work being performed in the intake structure. However, the CCW 1-1,2-1, and 2-2 heat exchangers had been cleaned of macrofouling and waterjetted more frequently than the CCW 1-2 heat exchanger during this time period. As a result, these CCW heat exchangers did not develop a microfouling layer equivalent to that of the CCW 1-2 heat exchanger. The CCW 1-2 heat exchanger was not waterjetted or scraped between the 1990 period of high potential microfouling until after the GL 89-13 test in February 1991. This is consistent with the high level of microfouling found in the 1-2 CCW heat exchanger at the time of the test. The CCW 2-1 and 2-2 heat -

exchangers were cleaned and batch chlorinated with a frequency typical of normal practices.

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The average dry weight of the microfouling samples collected from the 1-2 CCW heat exchanger in February 1991 was 7.9 g. In contrast, the dry weight of samples collected from the 2-2 CCW heat exchanger in June 1991 and the 2-1 CCW heat exchanger in August 1991 (prior to their performance testing in September 1991) averaged 0.3 and 0.4 g, respectively.

PG&E believes that if the 1-2 CCW heat exchanger had been cleaned and waterjetted as frequently as the other CCW heat exchangers prior to the test, it would have performed similarly to the Unit 2 heat exchangers. However, in order to confirm this, additional testing will be performed on the heat exchangers during the upcoming Unit 1 and Unit 2 refueling outages.

In addition, PG&E requested HOLTEC, International to analyze the GL 89-13 test data for the CCW 1-2 heat exchanger. The HOLTEC model was specifically developed for GL 89-13 evaluation and has been widely used by the nuclear power industry. It has been validated using an approved software quality assurance program and has been used in audit responses; therefore, it is considered a good validation of the HTC-STX program. The preliminary results of the HOLTEC model reanalysis of the GL 89-13 test data predicted the CCW 1-2 heat exchanger performance at nameplate condition would be 101 percent with a 95 percent confidence level. At the ASW design basis specified in WCAP-12526, Rev.1 condition, the preliminary result would be 100.3 percent with a 95 percent confidence level. For comparison, the HTC-STX results at the Yuba nameplate condition were 98.7 +/- 1.2 percent and at the ASW design basis specified in WCAP-12526, Revision 1 condition, 98.0 +/- 1.2 percent. A January 1994 resolution of the uncertainty analysis resulted in lowering the overall uncertainty from 1.5 to 1.2 percent for the CCW 1-2 heat exchanger. This reanalysis confirmed the validity of the HTC-STX computer program.

EVALUATION OF EFFECTS OF ASW FLOW AND OCEAN TEMPERATURE ON ASW SYSTEM OPERABILITY I

Two important key parameters, related to heat transfer capability, are the amount of ASW flow through the heat exchanger and the temperature of the ASW.

ASW Flow: ASW flow is affected by the number of pumps in operation, actual pump performance, tide level, and the cleanliness of the piping system, traveling screens, and the CCW heat exchanger.

ASW Temperature: Ocean temperature varies daily and seasonally. While the daily average ASW Fahrenheit temperature typically runs in the 50s, the average will occasionally rise into the low 60s.

f ASW design basis heat removal capability is a function of ASW flow, heat transfer area, and temperature (with a fouling factor to account for the fouling mechanisms )

described above). The ASW temperature and flow requirements interrelate to j provide an equivalent peak heat removal capacity. For example, the heat removal f provided by 10,750 gpm at 64*F is equivalent to the heat removal provided by 9,150 gpm at 58 F.

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The CCW heat exchangers must be maintained in accordance with good industry  ;

practice for heat exchangers in seawater duty to assure that significant fouling or blockage does not occur. Sufficient ASW flow to meet design basis requirements ,

must also be maintained. Assurance of adequate flow is provided by the )

performance .of STPs M-26 and P-7B.

STP M-26 is performed monthly. The acceptance criteria for STP M-26 have been established based on curves in Westinghouse WCAP-12526, Revision 1, which  :

provides the acceptable combinations of ASW flow and ocean temperature. l STP P-78, " Routine Surveillance Test for ASW Pumps," is performed quarterly in i accordance with ASME Section XI to measure ASW pump flow and vibration.

The STP M-26 flow measurements have historically varied more than the STP P-78 i flow measurements, even though both flow measurements are taken at the same i ASW annubars. Recent flow measurements taken with Contro!otron instruments and  ;

dye dilution tests show that the annubars appear to indicate less than the actual flow rate. j EVALUATION OF CURRENT OPERATIONAL LIMITS ON DIFFERENTIAL PRESSURE The NRC Inspection Report identified Unresolved item 50-275/93-36-03 relating to the technical basis for the high alarm setpoint established by PG&E for differential ,

I pressure (dp) across the heat exchangers. In particular, the Inspection Report stated that the alarm setpoint was set at 140 inches WG. Pursuant to an Operations Department standing order, cleaning of the heat exchangers is initiated when the differential pressure is about 130 inches WG. Based on the inspector's observations, a concern was expressed that the 140 inch WG setpoint was inconsistent with the amount of macrofouling experienced by the heat exchangers at a lower differential pressure, and therefore the potential existed that at levels below 140 inches WG a heat exchanger might be excessively fouled and outside its design basis. This observation was based upon the understanding by the inspector that the heat exchanger contained a total of 2 percent margin beyond design.

The following is an evaluation of the NRC concerns regarding the technical basis for the current differential pressure alarm setpoint:

Differential pressure is a diagnostic tool and cannot, by itself, quantitatively be used to determine operability (see PG&E letter DCL-88-215, dated September 13,1988).

This is based on a consideration of the uncertainties associated with any established dp limit. These uncertainties include: measurement errors in ASW flow, variation and uncertainty in heat exchanger clean dp levels, uncertainty and drift associated with dp instrumentation, and modeling uncertainties of actual pressure and flow losses that are associated with the heat exchanger design and macrofouling.

However, a dp setpoint can be used as a threshold indicator. When the established threshold is reached, the heat exchanger waterbox and tube conditions should be 6352S 9

inspected to assure that actual conditions in the heat exchanger are consistent with those assumed.

PG&E has established thresholds (limits) for the CCW heat exchangers. The limits have been established based on empirical evidence collected by PG&E biologists and engineers as to the actual amount of macrofouling observed in the heat exchanger channel head, and on the tube sheet, when the heat exchangers were removed from service for cleaning over the past nine years of operation. In addition, PG&E has developed a model of hydraulic pressure loss for the CCW heat exchangers which can be used to determine the reasonableness of the empirical evidence cited above.

These sources of information are discussed below.

The dp setpoint at DCPP has changed over the years as new information has become available. Early in plant operation the setpoint was at 110 inches WG, a level which immediately caused operational problems. Inspection of heat exchangers in alarm at 110 inches WG indicated that the heat exchangers had little to no macrofouling at this level. PG&E moved the setpoint over the next several years in an attempt to find the optimal balance between cleaning the heat exchanger frequently enough to l assure adequate heat transfer, and not cleaning the heat exchanger so often as to increase the overall risk to plant safety of having the heat exchanger out of Service.

PG&E established a two-tiered limit of a 130 inch WG cleaning criterion, coupled with a 140 inch setpoint at which the heat exchanger is declared inoperable and removed from service, based on the observed low level of fouling during heat exchanger cleanings at these limits of dp.

To further substantiate the empirical evidence and engineering judgment that established the two-tiered limit, PG&E developed a conservative model to estimate differential pressure losses across the CCW heat exchangers. A brief discussion of the concepts used in the PG&E differential pressure model follows.

The PG&E model assumes that dp consists of two components: hydraulic losses across the heat exchanger and differences in static head between the inlet and outlet waterboxes. l The hydraulic losses across the heat exchanger are composed of losses due to turbulence effects at the inlet / outlet of the tubes and waterboxes, and losses through the tubes themselves (including a slight increase in dp due to the tube inserts installed at the tube inlets). This component of measured differential pressure is a direct function of the velocity of the water passing through the heat exchanger and its tubes and thus is a function of the ASW flowrate. However, the velocity of water through the tubes is not only a function of the total ASW flowrate, but also the number of tubes available for flow. Thus, as tubes become plugged (e.g., due to blockage as a result of macrofouling), the hydraulic loss component for the dp )

increases. i l

I The other component considered in the PG&E model is the difference in static head I

between the inlet and outlet waterboxes. As a result of testing performed in 1989, it was established that the inlet waterbox level was full. This same testing was l

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1 interpreted as indicating a void in the outlet waterbox of approximately 30 inches WG. The difference in waterbox level would be reflected in an increase in measured dp. Recent testing using ultrasonic measuring techniques has shown that the levelin the outlet waterbox is being maintained at 5

• 2 inches of the top during operation with one pump aligned to one heat exchanger. The previously measured 30 inches is now attributed to a combination of both the water elevation differences and velocity losses in the outlet waterbox. Thus, the static head differential between the inlet l and outlet waterboxes is assumed to be 5 inches instead of the previously assumed l 30 inches. This reduces the contribution to measured dp due to waterbox voids. l l

CCW heat exchanger performance is a function of several variables: ASW flowrate,  !

ASW temperature, and fouling. CCW heat exchanger performance increases with increasing ASW flow and decreasing ASW temperature. Heat transfer across the l tubes is a function of the thermal resistance of the tube walls as well as the buildup  !

of insulating materials on the tube surface (e.g., microfouling and scale). The i available heat transfer area is a function of the number of tubes through which {

cooling water can flow. This is affected by macrofouling that may block flow through some of the tubes. As indicated above, this accumulation of macrofouling is l' reflected by an increase in dp measured across the heat exchanger. Preliminary analysis has shown that the negative impact on heat transfer of partially blocked tubes is smaller in magnitude than the negative impact of fully blocked tubes at l equivalent dp levels.

PG&E then conservatively determined the extent to which available CCW heat j exchanger margin was reduced as effective area of the heat exchanger was lost due l to assumed macrofouling. PG&E used the margin available between design heat i transfer capacity and the heat transfer capacity determined during the GL 89-13 l testing using the Unit 2 data as a baseline. These test results demonstrated that the l heat transfer capability for a clean heat exchanger was 109 percent (including l uncertainty) of its design capacity. As discussed above, these Unit 2 data are the l most representative of baseline CCW heat exchanger capacity. PG&E modeled  ;

increasing numbers of fully blocked tubes until the calculated reduction in heat i exchanger performance was equivalent to its design capacity. These calculations showed that at nominal flow conditions, approximately 20 percent (246 if the tubes) could be fully blocked and the heat exchanger would still be able to reject the design heat loads. Combinations of higher ASW flow rates and/or lower ASW temperatures could allow even more tubes to be blocked. This process was repeated for a variety of ASW flow and ocean water temperature combinations since both factors independently influence available heat exchanger capacity. Once PG&E established the number of fully blocked tubes equivalent to a maximum allowable fouled condition, PG&E calculated a predicted associated increase in pressure drop. This .

predicted increase in pressure drop must be added to the baseline pressure drop of a l

' clean" (no tubes plugged) heat exchanger. Using this methodology, maximum aliowable dp limits were predicted. The methodology utilized by PG&E has been reviewed in detail by an industry heat exchanger expert and found to be a reasonable modeling approach.

I 6352S 11

This methodology was then used to generate a family of curves for various combinations of ASW flow and ocean water temperature that would assure the CCW heat exchanger capability to remove the design basis heat load. Recent pump flow testing data have shown the calculated allowable dp is approximately 135 inches WG at 64a F for the most limiting pump and heat exchanger combination. Relaxing the conservatism in the model to allow some partially blocked tubes, thereby making the model more realistic, is expected to increase this maximum allowable dp above 140 inches WG. The remaining three heat exchangers in similar service showed allowable operating differential pressures in excess of 140 inches WG. These values correspond well to the dp limits currently in place at DCPP and reconfirm the adequacy of the current two-tiered dp control strategy. These calculations were conservatively based on 64' F ocean water temperatures. Even without accounting for partially blocked tubes, calculated allowable dps would be greater than 140 inches WG for all heat exchangers at ocean temperatures of 62*F and lower, which DCPP generally has experienced during its operating history. This model contains limitations such that it should be applied to heat exchangers where the " clean" baseline operating conditions are firmly established. Since this model has only recently been developed, benchmark data have not been taken.

Notwithstanding, PG&E has taken the results from this model into consideration for the davelopment of future ASW operating criteria. These criteria will be used to assess the condition of the CCW heat exchangers. Specifically, PG&E will maintain the following operating limits for the CCW heat exchangers:

• Consistent with PG&E's engineering judgement and evaluation of past empirical data and as generally confirmed by the analysis presented above, the high differential pressure alarm setpoint will be maintained at 140 inches WG.

• Based on the confirming information provided by conservative modeling, PG&E will maintain the cleaning criteria at 130 inches WG.

e To demonstrate heat exchanger cleanliness, regardless of dp, each heat exchanger will be inspected at a frequency of six months, and will be cleaned as required.

PG&E will maintain the described limits and inspection for the current operating cycles. Since PG&E will be performing functional tests of the CCW heat exchangers during the next refueling outages, PG&E will reassess, as appropriate, these limits based on the outcome of these tests.

In summary, these criteria, combined with the ongoing chlorination and maintenance programs, assure that the system will be capable of performing its design basis function.

6352S ADDITIONAL OPERATIONAL. AND MAINTENANCE PROGRAMS With the combination of monitoring dp, surveillance testing, and additional .

operational and maintenance activities, the ASW system operability is assured. '

These additional activities, summarized in Table 1 below, include periodic preventive '

maintenance and inspections of the traveling screens, pump bays, expansion joints and piping coatings in the ASW flow path, monitoring and cleaning of the CCW heat exchangers as described above, and other STPs for the check valves and power actuated valves in the system.

TABLE 1 MAINTENANCE AND TESTING ACTIVITIES Equipment / Parameters Procedurel Frequency Work Order Traveling Screen >

Corrosion / Damage PM 41722 18 months Pump Bays Corrosion / Debris PM 52070 18 months >

Pumps /Disch. Check Valves Flow / Vibration STP P-78 Quarterly Expansion Joints Cracks / leaks PM 40010 Annually Power Actuated Valves Stroke Time STP V-3F Quarterly Piping Flow STP M-26 Monthly Temperature STP l-1 A 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Coating /Biofouling (Inspection) STP M-235 6 years Biofouling (Chlorination) ECG 17.2 .-

Heat Exchangers Flow - STP M-26 Monthly Differential Pressure PK01-01 Continuous Biofouling/ Calcification PM 53586 - As needed Biofouling (Chlorination) ECG 17.2 -

Coating / Corrosion PM 51872 18 months Tube Cleaning / Scraping /Waterjet MP M-56.16 18 months I

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EVALUATION OF PUMP RUNOUT The NRC Inspection Report identified a concern regarding potential ASW pump ,

runout under certain conditions. The concern had previously been identified in PG&E l surveillance report SOA-93-0031.

" Runout" describes a condition of pumping higher flow rates than the pump's design performance curve. Specifically, runout concerns are associated with operating the ASW pump at high flow conditions such that cavitation, pump motor tripping, and/or pump overheating may occur. PG&E has reviewed its calculations, ASW pump l testing results, and data from the pump manufacturer, and concluded that acceptable net positive suction head (NPSH) is available for the runout flow conditions, and that the associated brake horsepower (BHP) and temperatures will not jeopardize pump motor operation.

At ocean water temperatures of 64*F or greater, a second heat exchanger is placed in service to assure that sufficient heat transfer capability is available for design basis accident heat loads. It is for this configuration of one ASW pump supplying cooling water to two CCW heat exchangers that ASW pump runout is predicted.

The ASW pump runout concern was based on calculated flows using the highest measured flow reading of the STP M 26 test results. Given the test data and correcting it for the limiting conditions (i.e., high and low tides, minimum flow resistance through the heat exchanger, and fully open CCW heat exchanger valves) with one pump supplying two heat exchangers, the predicted flows were 16,100 gpm and 15,100 gpm for high and low tides, respectively. This was determined by engineering personnel to not represent a challenge to the operability of the ASW system. A review of actual pump performance records determined that the predicted high flows could not be achieved with the existing equipment and system design configuration. Testing was also performed in 1989 for various configurations of the ASW system (TP TB-8903), which provided additional data to support the judgement that the postulated runout conditions were not probable. - A flow of 13,540 gpm and a brake horsepower of 439 HP were measured for one pump supplying two CCW heat exchangers.

The design calculation for the ASW system estimated flows of 15,100 gpm and 14,500 gpm for high and low tide conditions, respectively, when aligned with one pump supplying two heat exchangers. The design calculation addressing ASW pump NPSH requirements concluded that the NPSH available at a high tide exceeded the required NPSH by several feet; the NPSH available at low tide was below the required NPSH by approximately two feet. The low tide condition was determined to be acceptable, although minor cavitation may occur, based on the fact that the difference between the required and available NPSH is small and the operating condition would be of a short duration (until tide level increased within a few hours).

Damage due to cavitation occurs over a long period of continual operation (months to  !

years) in a condition of insufficient NPSH available, j i

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Design evaluation of the maximum brake horsepower for the ASW pumps estimated the BHPs to be approximately 450 HP, over the range of operating design flows.

This design value was also supported by information provided by the pump manufacturer, who stated that at a flow of approximately 13,000 gpm, the horsepower curve peaks at 450 HP and remains flat out to 15,000 gpm and beyond.

However, it was anticipated that ASW pump operation may result in brake horsepowers that exceed the design maximum of 450 HP. As a result, further evaluation by the motor manufacturer concluded that the ASW pump motors are capable of operating at 465 HP without exceeding their design limits.

To confirm PG&E's conclusions regarding runout, plant test TP TB-9409, "ASW System, Test of Alternate Configurations," was conducted on February 4-8,1994.

The ASW pump and test data were evaluated and confirmed that cavitation and motor overheating / tripping are not a concern. The flow results correlated well with  !

I design calculations. Test flows were adjusted to design basis low tide conditions

(-4.1 ft mean sea level) and, only the configuration of one pump supplying two CCW heat exchangers, where cavitation is predicted. The cavitation is judged to be minor l i

and acceptable for operation because of the minimal difference between available and required NPSH, and the short duration of the extreme low tidal condition. The tests confirmed that the ASW pump motors may operate at brake horsepowers in excess of 450 HP with a maximum of less than 465 HP for the design operating conditions. The test results also confirmed that the motor bearing and stator temperatures would remain within their design basis limits.

PG&E consulted the ASW pump manufacturer and an independent pump expert on the impact of operating the ASW pumps in a condition where the NPSH available l was less than the required amount. It was their judgement that the pump will continue operating; however, there may be a slight drop in performance at the point where the required NPSH for the flow was not available. This operating condition would result in cavitation, and eventual impeller and pump damage if operated continually over a long period of time (months to years). The impact of the cavitation at the postulated condition was determined to be of very low consequence since low NPSH margin occurs only at low tide conditions in the one pump, two heat exchanger configuration. It was also determined that the impact of operating at l

higher flows with cavitation would not result in a significant, if any, increase in BHP requirements since the pump performance would begin to drop off. Engineering calculations will be revised to incorporate the results from test TP TB 9409. ,

In summary, PG&E has evaluated the potential for ASW pump runout and concluded that it will not affect the capability of the system to perform its design function.

This conclusion is based on actual testing, pump and motor manufacturers' information, and engineering calculations.

CONCLUSION REGARDING CURRENT ASW SYSTEM OPERABILITY The CCW heat exchangers are capable of meeting their design basis requirements when maintained in a clean condition and operated within design basis parameters.

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PG&E's current maintenance, operational, and testing programs for the heat  ;

exchangers assure that they will continue to be maintained sufficiently clean of macrofouling and microfouling to allow them to perform their design basis function.

Based on the above evaluation, the ASW system is operable and will continue to perform its intended safety function.

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PG&E Letter No. DCL-94-037 ENCLOSURE 2 PREUMINARY SAFETY EVALUATION OF PAST OPERABlUTY OF ASW AND CCW SYSTEMS Introduction As described in Enclosure 1, key parameters affecting the performance of the ASW and CCW systems include: macrofouling and microfouling, ASW flow, and ocean temperature. An extensive review of historical maintenance, testing, operational, and biological f actors was performed to identify time periods with a high potential for macrofouling and microfouling. During this review of past operation, specific periods of time have been identified during which one or more of these key parameters may have been outside current acceptance criteria. These time periods, and the safety significance of the associated fouling, are discussed below.

Biological Fouling Conditions The potential for significant microfouling of CCW heat exchanger tubes occurs when certain conditions are met. These conditions include:

e An upwelling of cold, nutrient-rich water from deep ocean layers, which occurs as a result of strong northwesterly winds that characteristically blow during the j spring, e A period of high ocean temperatures, which, following an upwelling period, allows the microorganisms to " bloom." Experience indicates that ocean  ;

temperatures of approximately 58*F or greater must be reached over a several l week period for the " bloom" to occur. j i

e The chlorination system is out-of-service for a considerable period prior to and j during the " bloom." Without chlorination during the " bloom" period, microfouling  !

could form on the tubes of the heat exchanger. If chlorination is restarted after the " bloom" has occurred, further microfouling is stopped. However, residual material placed by the microorganisms remains in the tubes as a coating and continues to impact heat exchanger performance. Once deposited, waterjetting or scraping of the tubes is needed to remove the residual material.

i Bounding Microfouling Condition l PG&E's evaluation of maintenance and operational practices over Diablo Canyon's l

operating history indicates that the bounding conditions for potentially significant 6352S 1

microfouling only occurred during July and August of 1990. Prior to this period, upwelling of nutrients had occurred and was followed by a period of ocean warming.

As a result, a microfouling " bloom" occurred. PG&E's analysis indicates that microfouling reached significant levels in July 1990 as ocean temperature exceeded l 58'F. In addition, the chlorination system was out-of-service during this period while PG&E was replacing cast iron piping in the system. When batch chlorination was restored on August 21,1990, further microfouling ceased. However, the residual material from the microorganisms remained in the CCW heat exchanger tubes until waterjetting or tube scraping was performed. PG&E's review indicates that there were no other time periods when the lack of chlorination and maintenance was coupled with favorable environmental conditions for microfouling.

1 Of the four CCW heat exchangers, the 1-2 heat exchanger was the most susceptible to microfouling based on its chlorination, maintenance, and operating history. The j remaining three heat exchangers received waterjet cleanings between the period of i high microfouling potential and the performance of the GL 89-13 performance I testing. In addition, two of the other three heat exchangers were operated less  !

frequently during the period of high microfouling potential. l The CCW 1-2 heat exchanger was not waterjetted or scraped during the period from August 1990 until after the performance of the GL 89-13 performance test in February 1991. PG&E believes that the heat transfer microfouling characteristics of the CCW 1-2 heat exchanger during its associated GL 89-13 testing represent the bounding microfouling case.

PG&E evaluated the highest macrofouling that may have existed coincident with high microfouling. During August 1990, the CCW 1-2 heat exchanger was taken out of service for cleaning with a recorded dp of 130 inches. It was not again taken out of ,

service until the test in February 1991, at which time the recorded dp was 110 l inches. Thus, the August 1990 dp of 130 inches represented the highest I macrofouling reached during this bounding microfouling period. The level of macrofouling associated with a dp of 130 inches, coupled with an assumed level of microfouling found during the testing of the CCW 1-2 heat exchanger, represents the most limiting fouling of a CCW heat exchanger.

Bounding Macrofouling Condition PG&E's review of macrofouling data identified periods of operation at an elevated dp (greater than 140 inches). The historical data focused attention on a period from August 1986 to March 1988. The apparent bounding case of macrofouling identified in this period occurred on November 8,1987, when CCW 1-2 heat exchanger was removed from service with a dp of 170 inches in conjunction with an ocean water temperature of 61

• F. A review of environmental conditions associated with this period of high dp determined that coincident conditions required for significant microfouling did not exist. PG&E believes that microfouling levels at that time were consistent with the levels observed during the Unit 2 CCW heat exchanger GL 89-13 tests.

6352S PG&E has evaluated this condition of high macrofouling. Based on the available information, PG&E's evaluations have determined that the bounding conditions of high macrofouling were not as limiting as the conditions which existed in August 1990. Thus, the condition of high microfouling with a 130 inch dp is the bounding fouling case.

Safety Significance PG&E has analyzed the bounding case for high microfouling coincident with a 130 inch dp as described above for safety significance. These analyses were performed using the old Westinghouse Mass and Energy (M&E) release model, which is the licensing basis for DCPP. Additionally, a newer more realistic Westinghouse M&E release model with a methodology licensed for use at other Westinghouse plants was used with best estimate values and other realistic inputs for certain parameters. This model more accurately reflects the physical phenomena that occur. Although not licensed for use at DCPP, this new model can be used to determine the M&E releases expected for the current and past plant configuration.

The impact of bounding case fouling on the containment integrity analyses was performed by Westinghouse using the old (current licensing basis) M&E release model. Westinghouse evaluated the design basis LOCA as well as the limiting MSLB accidents for impacts on containment pressure and temperature. The conclusion of l these evaluations is that the containment design basis pressure and temperature l would not have been exceeded during a postulated LOCA or MSLB.

The design basis CCW temperature limits allow a transient temperature maximum of 132 F for 20 minutes. The temperature limit for continuous operation is 120' F.

PG&E has evaluated the impact of the bounding case fouling on the limiting post-LOCA CCW temperature transients. Using the old (current licensing basis) M&E release model, PG&E and Westinghouse have determined that the peak CCW temperature may have exceeded the design basis CCW temperature during the i injection phase following a LOCA. l Westinghouse then perfo'medr an analysis of the containment temperature transient following a LOCA using the new, more realistic M&E release model. The results of these analyses were used by PG&E to evaluate the CCW temperature transient that would result from the containment conditions calculated by Westinghouse using the new M&E release modeling methodology. These evaluations concluded that the CCW temperature remains below design limits during the injection phase of the accident, but could have exceeded its design basis temperature limits in recirculation for an extended period if operator action is not taken.

The potential for the CCW system to overheat during the post-LOCA recirculation phase of an accident was previously identified by PG&E in 1991. LER 1-91-018,

" Component Cooling Water System Outside Design Basis," reported that the heat load during cold leg recirculation may exceed the CCW system design basis temperature limits. Specific recirculation transient analyses were not performed. At 6352S that time it was reported that operator action to keep CCW temperatures within design limits was required if the two ASW pump /two CCW heat exchanger configuration could not be established. The safety significance conclusions regarding the bounding case of fouling are similar to those reported in LER 1-91-018.

Guidance to address conditions when both ASW pumps and CCW heat exchangers were not available was incorporated into step 3.d of EOP E-1.3, " Transfer to Cold Leg Recirculation," in response to the LER. The potential for elevated CCW temperatures identified above is due primarily to the heat loads that were imposed on the system during recirculation, and not specifically caused by the identified heat exchanger fouling. Preliminary analysis has indicated that, had this EOP guidance been in place at the time that the bounding conditions existed, the CCW system temperature, using the new M&E release model, would have remained within its design basis.

To bound the conditions in place during the 1990 high macrofouling and microfouling case, as well as the 1987 high macrofouling case, PG&E evaluated the CCW temperature transient assuming likely operator actions prior to revising the EOPs even though more timely operator actions were in place for the 1990 case. Prior to the 1991 revision of EOP E-1.3, EOP E 0, " Reactor Trip or Safety injection," was revised in 1989 to require placing a second CCW heat exchanger in service when only one ASW pump is available (post-LOCA). PG&E developed a timeline of actions which, while not formally proceduralized, are believed to be representative of those actions that would have occurred prior to the 1989 EOP changes. The timeline would have operators secure two CFCUs 15 minutes after the start of recirculation in response to high CCW temperature alarms and subsequently place the second CCW heat exchanger into service 10 minutes later. This timeline bounds both the 1990 and 1987 cases.

Assuming operator action as described above, the limiting CCW temperature transient was evaluated for the bounding 1990 high micro- and macrofouling case.

The peak CCW temperature based on this scenario was approximately 136' F and the cumulative time above 120' F was approximately 50 minutes. The impact of the elevated CCW temperatures on the components of the vital CCW headers was evaluated. Westinghouse analyzed the impact of the CCW temperature profile and has determined that the Si and RHR pumps and the CFCU fan motors would perform their design basis function. The CCW pump manufacturer confirmed that the CCW ,

pumps would perform their design basis function at the elevated CCW temperatures. l The post-LOCA sampling system may have been temporarily disabled by the elevated CCW temperatures. However, the ability to assess core damage remained available from alternate proceduralized means. The centrifugal charging pumps (CCP) cannot be shown to continue to be available at these elevated temperatures although the exact point of failure is not known. However, the CCPs are available for the entire injection phase of the accident. Regardless of the CCPs availability for recirculation phase, Westinghouse and analyses have determined that during the recirculation phase, other ECCS pumps are available to perform required ECCS functions.

Based on the foregoing detailed analysis of this event, PG&E concludes the following:

6352S 4

• The fouling identified on the CCW heat exchangers would not have resulted in the containment design pressure or temperature being exceeded.

• The CCW design basis temperature limits would only have been exceeded during post-LOCA recirculation.

• Considering the CCW temperature transient, containment and core cooling functions would not be significantly affected. All vital components served by the CCW system would have continued to perform their design basis function, or redundant equipment would have been available to perform these functions.

Accordingly, this event had no safety significance and the health and safety of the public would not have been affected.

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PG&E Letter No. DCL-94-037 ENCLOSURE 3 PG&E'S RESPONSE TO NRC INSPECTION REPORT NOS. 50-275/93 36 AND 50 323/93-36 NRC Inspection Report Nos. 50-275/93-36 and 50-323/93-36 identified a number of NRC concerns and open, followup, and unresolved items regarding past and future operability of the ASW system and PG&E's implementation of controls to assure continued ASW system operability. PG&E's response to each of these items in the Inspection Report is provided below.

NRC Inspection Report Followup and Unresolved items NRC Followuo item 93-36-01 noted that the ASW system flow test acceptance values did not include a simple value for minimum flow, but provided a series of curves dependent on the ocean and CCW temperatures. The inspection noted that PG&E stated the test acceptance values were derived from a Westinghouse study, WCAP-12526, Revision 1, " Auxiliary Salt Water and Component Cooling Water Flow and Temperature Study for Diablo Canyon Units 1 and 2," dated June 1992. The study is one of three different design bases described in PG&E's design criteria memorandum, DCM No. S-178, Revision 2, " Auxiliary Saltwater System." The inspection noted that PG&E had indicated that the revised design bases had not been reviewed by the NRC technical branches. The inspection records stated that acceptability of PG&E's revised design bases is considered an open item. ,

I PG&E Resoonse The original design basis for the ASW system was provided by Westinghouse. This design basis required the ASW system to remove a post-LOCA heat load of l 252 X 10' Btu /hr. The heat load was based upon maximizing containment pressure by assuming the loss of a vital electrical bus which causes a loss of power to two CFCUs. This scenario yielded conservative containment LOCA pressures.

In 1983, a scenario was determined to be more limiting to the ASW system heat load. This scenario assumed that during a LOCA no vital bus failure occurred, but assumed the active failure of an ASW pump. In this scenario, the maximum l post-LOCA heat load is transferred to the five CFCUs and then to the ASW system l 8

through the CCW heat exchangers. This maximum heat load is 325 X 10 Btu /hr. l Since 1983, this transient has been recognized as the Diablo Canyon design basis for i the ASW system as noted in NRC SSER 16. PG&E has not changed this design basis.

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The Westinghouse study in WCAP-12526, Revision 1, does not change the ASW heat load design basis. This WCAP provides equivalent heat removal using ASW flow and seawater temperature as variables.

Actions Being Taken PG&E will review the current ASW basis with the NRC technical staff.

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NRC Unresolved item 93 36-02 noted an apparent failure to provide complete and accurate information to the NRC regarding the ability of the CCW 1-2 heat exchanger to meet the design basis heat load. I PG&E Resoonse Summary in regard to the inspection Report's concerns with the accuracy and completeness of information provided by PG&E in response to GL 89-13, PG&E is committed to the highest levels of accuracy and credibility in the information it provides to the NRC  !

and the public, and takes very seriously any issue raised relating to this commitment.

Based on its comprehensive review of all relevant documents and information, PG&E i believes that its statement regarding the results of heat exchanger performance l l

testing was accurate and complete when considering the guidance in the GL, as well as the previous information PG&E had provided the NRC regarding the limitations and inconclusiveness of such testing. However, PG&E agrees that its engineering evaluation of the test results should have been more comprehensive.

At the time PG&E letter DCL-91-286, dated November 25,1991, was submitted, PG&E believed that its statements were accurate and complete. GL 89-13, and Supplement 1, provided guidance regarding the level of detail required in licensee responses (see GL 89-13, Supplement 1, Questions and Answers I.C.1 and Ill.C.2).

PG&E believes that its response was consistent with this guidance particularly when considered in context with information that PG&E had provided the NRC in PG&E letter DCL-90-027, dated January 26,1990, regarding the limitations and inconclusiveness of the heat exchanger testing.

PG&E consulted an industry heat exchanger expert and further evaluated the CCW 1-2 heat exchanger testing results. PG&E now concludes that testing results did not meet design basis heat trans'er requirements when analyzed using the Heat Transfer Consultants Inc., HTC-STX computer program due to the effects of microfouling at the time of the CCW 1-2 heat exchanger test. Based on the analysis presented in Enclosure 1, if the CCW 1-2 heat exchanger had been cleaned of microfouling prior to the conduct of the test, the heat exchanger would have passed. Current chlorination, maintenance, and operating practices assure the cleanliness of all CCW heat exchangers.

Background

NRC GL 89-13, item 2, recommended that a test program be developed to verify the heat transfer capabilities of safety-related heat exchangers cooled by service water.

It also indicated that an alternative acceptable to the NRC is frequent regular maintenance of a heat exchanger in lieu of testing. PG&E's response to GL 89-13 relied predominantly upon the established maintenance program, but heat transfer tests were performed to establish baseline heat exchanger nominal performance. i 6352S )

. s During the evaluation of the testing results, PG&E used an industry computer program, HTC-STX, to perform the analysis. The computer model predicted that CCW 1-2 heat exchanger was performing at 1.3 percent less than the design (nameplate) heat transfer capability. However, the 1.3 percent difference was judged to be within the range of the heat balance and measurement accuracy. Since all three of the other CCW heat exchangers exceeded their design heat transfer capability and all four CCW heat exchangers were designed similarly, PG&E concluded all four of the heat exchangers would meet their design basis requirements. This conclusion also appeared consistent with the guidance in GL 89-13, which recognized the Sherent limitations of baseline testing programs.

Recently, HOLTEC International was contacted to reanalyze the CCW 1-2 heat exchanger test data. HOLTEC is a qualified supplier of engineering services to PG&E, and HOLTEC indicated that their computer code has been validated. The preliminary analysis demonstrated that using the HOLTEC model the CCW 1-2 heat exchanger operated at 101 percent of design nameplate rating at the time of the test with a 95 percent confidence level.

For these reasons, the statement in DCL-91-286 factually reflected PG&E's engineering judgement at the time and was accurate and complete.

In retrospect, PG&E should have been more thorough in its analysis of the test results and should have documented the basis of accepting the CCW 1-2 heat exchanger test results. Consultation with an industry heat exchanger expert, who has worked previously on service water systems, has shown that: (1) the tests PG&E performed were generally well conceived and produced results of higher accuracy than PG&E believed possible at the time; (2) the test model used was more conservative in its results than the HOLTEC computer model used by the industry for similar GL 89-13 tests; and (3) the performance of the CCW 1-2 heat exchanger was due to biological microfouling present at the time of testing.

Actions Being Taken PG&E is taking the following actions to assure that test results are comprehensively evaluated and regulatory submittals provide sufficient explanatory information.

1. Procedure AD1.lD1, " Format, Content and Style of Procedures," was revised subsequent to the performance of the GL 89-13 heat exchanger testing to require that comprehensive acceptance criteria be documented for special tests.

Procedure AD13.lD1, " Conduct of Plant and Equipment Tests," will be further enhanced to require that deviations from acceptance criteria be documented and justified prior to acceptance of the deviation.

2. Design engineering, system engineering and licensing personnel involved with the GL 89-13 testing, analysis, and submittal preparation will be counseled on the thoroughness that must be applied when engineering judgement is used to justify acceptance of test deviations.

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3. A case study describing the situation, communications, corrective actions, and management's expectations on the events surrounding the ASW heat exchanger testing will be conducted with appropriate NPG personnel. The Directors of System Engineering, Mechanical Engineering, and Site Quality Assurance will present.the case study. PG&E believes that by using the Directors to lead the case study, a clear message of expectations on the high standards of thoroughness, clear communication, and delineation of responsibilities will be fully reemphasized to the technical staff.

6352S NRC Unresolved Item 93-36-03 noted an apparent failure to establish adequate dp l limits to ensure CCW heat exchanger operability.

r PG&E Resoonse Enclosure 1 provides a detailed description of the PG&E analysis which confirms the engineering judgement and empirical observations used by PG&E to establish current CCW heat exchanger dp setpoint limits.

Actions Being Taken Upon completion of additional heat exchanger performance tests scheduled for 1R6 and 2R6, PG&E will reevaluate the dp setpoint.

Enhanced ASW flow instrumentation will be installed with local readouts.

ECG 17.2 has been approved to provide administrative controls on the ASW chlorination system.

In addition to inspections performed when dp limits are reached, each heat exchanger will be inspected at a frequency of six months and cleaned as required.

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i NRC Unresolved Item 93-36-04 notes an apparent failure to develop a routine inspection program for the ASW system piping by the end of the fourth refueling '

outages, as committed to the NRC, and an apparent failure to provide accurate implementation status of the program in a letter to the NRC.

PG&E Resoonse Summery PG&E agrees that a permanent procedure was not in place for periodically inspecting i the ASW system piping at the time of the NRC inspection. However, a temporary l procedure had previously been issued for the initialinspection conducted during 1R4 I and 2R4. In addition, an Action Request (AR) was tracking the completion of the  !

final procedure prior to performance of the next inspection scheduled for refueling  !

outages 1R8 and 2R8. The surveillance procedure for piping inspection was issued j on January 12,1994, prior to its scheduled issuance date of June 1,1994. j

Background

GL 89-13 recommended establishment of a routine inspection and maintenance program for the ASW piping and components so that corrosion, erosion, protective coating failure, silting, and biofouling would not degrade the performance of safety-related systems. PG&E letter DCL-90-027, dated January 26,1990, indicated that procedures would be established by 1R4 and 2R4 for a routine inspection and maintenance program for the ASW system. Vhe letter also indicated that the appropriate interval for the performance of these inspections would be determined based on 1R4 and 2R4 observations.

PG&E conducted ASW system piping inspections during the 1R4 and 2R4 refueling -

outages. The piping inspections determined that the ASW system pipe lining was in excellent condition and capable of meeting its function as a protective barrier.

PG&E performed the 1R4 and 2R4 ASW piping inspections using temporary i

procedure TB-9048, "ASW Piping Inspection." The inspection found little macrofouling on the piping. Based on the results of the piping inspections, PG&E determined that the inspection frequency should be every fourth refueling outage.

Conversion of the temporary procedure, TB-9048,into an STP with a reinspection frequency of every fourth refueling outage was being tracked by ARs. This is' ,

consistent with PG&E's practice for new maintenance and surveillance programs. ]

Actions Taken To eliminate the concern regarding' issuance of the inspection procedure, STP M-235, "ASW Piping inspection," was issued on January 12,1994.  ;

l 6352S -7 I

NRC Followuo item 93-36-05 noted that the previous PG&E review of the design basis did not identify several important design basis issues. An evaluation of the need to reperform an assessment of the adequacy of the design basis for the ASW system is a followup item.

PG&E Resoonse Summery The evaluation of the capability of the ASW system to meet its design basis is provided in Enclosure 1.

Actions Being Taken

1. Additional CCW heat exchanger performance tests on both units will be performed to verify the adequacy of operational and maintenance practices to assure that the CCW heat exchangers meet design basis requirements. The tests will be conducted during the 1R6 and 2R6 refueling outages and will include dp measurement.

2. An " Integrated Problem Response Team (IPRT) will be conducted on the ASW, CCW and interfacing systems by the end of 1994. This IPRT will thoroughly and critically review these systems. Membership of the IPRT willinclude operations, quality services, maintenance, Westinghouse, and engineering personnel. Based on the results of the IPRT, DCM S-17B will be revised to provide additionalinformation on ASW system heat removal capacity.

4 6352S 8-

NRC Unresolved item 93-36-06 notes the apparent failure of PG&E to promptly resolve conditions adverse to quality, in particular the failure of PG&E's engineering organizations to resolve several Site Quality Assurance (SOA) surveillance findings in a timely manner.

PG&E Resconse Summary PG&E agrees that resolution of the SQA surveillance findings was not as thorough or comprehensive as PG&E management would expect. PG&E believes this stems from a failure of the organization to clearly focus on the operability consequences of issues raised in the SQA surveillance. As a result, appropriate priority was not placed on resolving the SQA issues by the responsible technical departments. This was not, however, a case where the surveillance issues were " dropped" by either SOA or the technical organizations. Significant followup activities occurred subsequent to the performance of the SOA surveillance in an attempt to bring issues raised to appropriate resolution. In addition to capturing unresolved issues in ARs, numerous phone calls, electronic-mails, and face-to-face meetings took place between SOA and responsible technical organizations. Twenty-one individual AR entries and eight electronic mails were sent between SOA and the engineering organizations on surveillance issues. The surveillance issues were the subject of discussion at two ASW system team meetings in early December 1993. Numerous j undocumented contacts (phone calls, discussions, etc.) occurred between the responsible organizations. The Manager of Nuclear Quality Services met with the SQA Director and lead auditor in early August to discuss the status of responses to the surveillance. At this meeting, the Manager instructed that a schedule be established for resolution of the issues. The SOA staff and line organizations subsequently met in August and agreed to a December 31,1993, complet;on schedule to resolve the technical issues. In addition, the Manager of Nuclear Quality Services raised the surveillance findings as an issue at the Nuclear Technical Services Emerging Issues meeting in San Francisco in August and November 1993 and also raised the issue at the DCPP Plant Manager's staff meeting to request that attention be placed on the surveillance response. However, despite the communication occurring on the issue, PG&E management personnel lost focus of the potential operability impact of the issues.

The delay in recognizing the potential operability implications of the SOA surveillance is in contrast with PG&E's demonstrated ability to thoroughly assess operability issues using procedure OM7.lD8, " Operability Evaluations," when presented with clear operability issues such as hardware failures or 10 CFR Part 21 notifications. In response to the SOA surveillance, PG&E technical organizations continued to conclude that the SQA surveillance issues did not represent current operability concerns. This was based on engineering judgement that existing maintenance and chlorination programs, described in response to GL 89-13, effectively assured current ASW system operability. The PG&E technical organizations, therefore, did not consider it necessary to enter OM7.lD8 to assess operability. The events were 6352S 9-

j exacerbated by a failure to take adequate ownership for resolution of the concerns, particularly at the Director and Senior Engineer levels within NPG. This led to a situation where periodic dialogue was occurring at the technical staff level but issues were not being fully resolved. Management inquiries as to what problems existed and what progress was being made were answered with responses that a technical resolution was proceeding.

As discussed in Enclosure 1, PG&E's subsequent evaluation demonstrated that (1) the dp setpoint is acceptable: (2) the ASW system has been operable since PG&E's t

implementation of GL 89-13; and (3) any untimeliness, therefore, did not adversely affect the public health or safety.

On December 15,1993, a Prompt Operability Assessment was issued to document operability of the ASW system. In addition, a Nonconformance Report was issued to 5 further investigate and resolve this concern. OE 93-16 was issued on December 30,1993, to provide further justification for ASW system operability.

PG&E engineering has subsequently provided comprehensive evaluation of the  ;

operability issues raised in the SQA surveillance.

To prevent recurrence of these events, PG&E will establish specific procedural  ;

guidance on the maximum time PG&E will allow staff level personnel to evaluate j questions involving potentially degraded structures, systems, and components before j the issue becomes a quality problem and is elevated to upper management as an operability issue for prioritization and resolution. Appropriate technical staff will be l trained and counseled on these management expectations. PG&E engineering management will also use outside experts, as appropriate, to help resolve technical issues that are at impasse and thus assure timely resolution.

I Actions Being Taken PG&E is taking the following corrective actions:

1. PG&E will establish an interdepartmental Administrative Procedure to resolve issues that raise questions regarding operability. The key elements will be: (1) address any issue of immediate operability concern using procedure OM7.lD8; (2) generate a Quality Evaluation (QE) for issues that are not a clear, immediate operability concern, if the issue remains unresolved for 30 days; (3) establish firm completion dates within the QE; (4) place issues exceeding these completion dates on an " Operability Concerns List;" (5) review the Operability-Concerns List at the NPG Officers / Managers weekly meeting; (6) assign specific responsibilities for resolution of Operability Concerns List items at the weekly meeting; and (7) review progress on assigned issues as identified by the Manager of Nuclear Quality Services.

2. A Human Performance Evaluation System (HPES) study will be performed. As part of the case study evaluation of the events of GL 89-13 testing, a 6352S 10

preliminary HPES study has been completed and identified the following items to be included in the case study discussion:

• The need for continuing vigilance in the depth and comprehensiveness of independent technical reviews of engineering evaluations and NRC licensing submittals.

e The need for clear test acceptance criteria for special tests and ,

documentation of results and deviations.

e The need for enhanced supervisory oversight of engineering evaluations that relate to potential operability concerns.

e The need for improved teamwork and communication between departments on issues relating to operability or quality concerns.

e The need for a questioning attitude on design basis issues that potentially affect the operability and margins for safety-related systems, structures, and components by all personnel including design engineers, system engineers, maintenance personnel, and operators.

l

3. An HPES followup evaluation will be performed to determine the effectiveness of I the case study' discussion on assuring that management expectations are clearly understood and followed by the technical staff.

4. As was previously indicated in the inspection Report response, appropriate technical personnel will be counseled on the need for thoroughness, completeness, and objectivity when analyzing questions that could impact operability.

5. Industry experts will be consulted, as appropriate, to provide resolution of technical issues at impasse.

4 6352S 11 f

(

NRC Unresolved Item 93-36-07 noted failure to use a validated computer code to predict design basis heat transfer capacity during heat exchanger capacity testing.

PG&E Resoonse Summary PG&E believes that the computer program used for evaluation of the heat exchanger testing results met the guidance provided in GL 89-13.

Background

GL 89-13, Supplement 1, provided the results of workshops held between the NRC and interested parties to clarify the requirements of GL 89-13. The response to question Ill.A.12 in GL 89-13, Supplement 1, on heat transfer testing indicated that off-the-shelf software that is reviewed for technical adequacy is acceptable to the NRC.

Heat Transfer Consultants Inc.'s "Shell and Tube Heat Exchanger Design and Rating Program" (HTC-STX) was the computer program used to predict the ASW heat exchanger performance at design basis conditions. This program is a design, rating, i and evaluation model for shell and tube heat exchangers in March 1991, the l HTC-STX model was benchmarked against the results of Yuba's heat exchanger design. The difference between the heat transfer coefficient given by Yuba and that calculated by the model was 2.6 percent, with the model predicting higher performance. In conversations with Yuba, they indicated that they incorporated a i 2 percent margin into their design. Consequently, in 1991 the comparison between the actual Yuba design and PG&E's model was actually 0.6 percent, which is excellent agreement. Based on these comparative results, PG&E's benchmark provided sufficient verification that the model could be used and the results accepted.

in response to this unresolved item, PG&E recently performed two independent calculations to demonstrate that the model is valid. PG&E contacted Heat Transfer Consultants, Inc. to obtain their theoretical formulation of the heat transfer coefficient. An independer't calculation was performed to evaluate the test fouling and predicted heat exchanger performance. These results demonstrate the validity of the computer program.

In addition, PG&E requested HOLTEC, International to analyze the GL 89-13 test data for the CCW 1-2 heat exchanger. The HOLTEC model was specifically developed for GL 89-13 evaluation and has been widely used by the nuclear power industry. It has been validated using an approved software quality assurance program and has been used in audit responses; therefore, it is considered a good validation of the HTC STX program. The preliminary results of the HOLTEC model reanalysis of the GL 89-13 test data predicted the CCW 1-2 heat exchanger performance at nameplate condition would be 101 percent with a 95 percent confidence level. At the ASW design basis 6352S specified in WCAP 12526, Rev.1 condition, the preliminary result would be 100.3 percent with a 95 percent confidence level. For comparison, the HTC-STX results at the Yuba nameplate condition were 98.7 +/- 1.2 percent and at the ASW design basis specified in WCAP-12526, Revision 1 condition,98.0 +/- 1.2 percent. A January 1994 issolution of the uncertainty analysis resulted in lowering the overall uncertainty from 1.5 to 1.2 percent for the CCW 1-2 heat exchanger. This '

reanalysis confirmed the validity of the HTC STX computer program.

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1 6352S ]

l NRC Followuo item 93 36-08 noted a concern regarding the effect of calcification (on the inner surface of heat exchanger tubes) on the heat exchanger capacity and the potentici effect of undetected tube plugging at the outlet.

l PG&E Resoonse PG&E believes there is very low potential for undetected tube plugging. Tube 1 plugging would be detected by heat exchanger dp. If significant calcification occurs, dp willincrease and heat exchanger cleaning would be necessary. If tubesheet cleaning of macrofouling does not effectively reduce dp, PG&E's maintenance organization would use effective mechanical cleaning methods to eliminate calcification and return the heat exchanger to service.

i Action Being Taken PG&E agrees that trending of the dp increase on each CCW heat exchanger would be useful in anticipating calcification and other buildup that may affect dp.

Consequently, PG&E will revise STP M 26 to require a formal trending program to monitor this parameter.

I F

6352S -14

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PG&E Letter DCL-94-049 l I

U.S. Nuclear kegulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Docket No. 50-275, OL DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Licensee Event Reoort 1-93-012-01 Auxiliarv Saltwater System Outside Desian Basis Due to Foulina Gentlemen:

Pursuant to 10 CFR 50.73(a)(2)(ii)(B), PG&E is submitting the enclosed revisi.on to Licensee Event Report 1-93-012 00 concerning the auxiliary saltwater (ASW) system being outside its design basis due to fouling. This revision is being submitted to report the results of a comprehensive evaluation of the past caDability of the ASW system to meet its design basis. This revision provides the safety significance, root cause, and corrective actions.

PG&E's comprenensive evaluation concluded that this event hao no safety significance and that tne health and safety of the puulic were not affecteo.

Sincerely, 3

I l I .w,y -

Greg y M. Rueger cc: Mary H. Miller Kenneth E. Perkins Sheri R. Peterson Diablo Distribution INPO DCO-93-EN-N022 Enclosure 6398S/DPS/2246

a 8 LICENSEE EVENT REPORT (LER) f AClutf madat til DOCKE'T ktsasp #7, , ,,og ,p DIABLO CANYON UNIT 1 01510101012i715i1i'!

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UCtwatt CDWT&CT Som T>es LAR 4171 e f r -% f *Mfe DAVID P. SISK - SENIOR REGULATORY COMPLIANCE ENGINEER I 805 I 545-442 comarurts one uma som LAcu conapomewT ean.una otscsssan en Tees maroat vizi s 41 ' n f t '* JMPonthT wasos at . .tpo a t cAgt $vsttM ;aMpontNT w pac. 6troata L I IiI I II I III III I IIl l II I III III sur tenan t AL as.coar (2rictro sia' ~~ "' l EXPECTED I SUSMtsstCW YE5 (if yes, c ornot e t e EXPECTED SUSMtss!ON wo 0 ATE N l x l 0Aff)

.. .a: al On Decemoer 30, 1993, at 1150 PST, with Unit 1 in Mode 3 (Hot Sta;1cby) at 0 percent power and Unit 2 in Mode 1 (Power Operation) at 100 percent power, PGLE ceterm1ned that the auxiliary saltwater (ASW) system and its assoc 1ated component cooling water (CCW) heat exchangers for both units may not have met their design cas1s for certain time perloos prior to implementation of continuous cnlorination.

Continuous chlorination was fully implemented in Septemoer and Novemoer 1992 for Units 1 and 2, respectively. This condition was reported to the NRC as a one-hour, non-emergency report in accordance with 10 CFR 50.72 (b)(1)(ii)(B) at 1150 PST on December 30, 1993.

The cause of this condition was an inadequate understanding of the effects of fouling on the CCW heat exchangers.

l The ASW systems for both units currently are operable given the present  !

maintenance, operational, and testing activities. These activities assure that i the ASW system will remain sufficiently clean such that fouling will not prevent j the system from performing its design basis functions. CCW heat e< changer tests j on both units will be performed to provide additional confirmation of the adequacy  ;

of operational and maintenance practices to assure that the CCW heat exchangers i meet their design basis requirements. An equipment control guideline was implemented to ensure compensating actions are taken if the ASW chlorination system becomes inoperable.

i l

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1. Plant Conditions Unit I and Unit 2 operated in various modes at various power levels while this condition existed.

11. Descriotion of Event A. Summary: >

On Decemoer 30, 1993, at 1150 PST, with Unit 1 in Mode 3 (Hot Standby) at 0 percent power and Unit 2 in Mode 1 (Power Operation) at 100 percent power, PG&E determined that the auxiliary saltwater (ASW) system (BI) and its associated component cooling water (CCW) heat exchangers (BI)(HX) for both units may not have met their design basis requirements for certain time periods prior to implementation of '

continuous chlorination. Continuous cnlorination was fully implemented in September and Novemoer 1992 for Units 1 and 2, respectively. This condition was reported to the NRC as a one-hour, non-emergency report in accorcance with 10 CFR 50.72 (b)(1)(ii)(B) at i 1150 PST on December 30, 1993. i i

B.

Background:

l. Design Following a loss of coolant accident (LOCA) or a main steam line  ;

break (MSLB) inside containment, the CCW system is required to i provide cooling water to the containment fan cooling units '

(CFCUs) (BK)(FAN) for containment heat removal, and to the various engineered safeguards features (ESF) pump coolers.

During the recirculation phase of the LOCA, the CCW system also cools the residual heat removal (RHR) heat exchangers (BP)(HX).

In order for the CCW system to perform its function, CCW water temperature must remain at or below 120*F for continuous operation and may exceed 120*F, up to a maximum of 132*F, fcr no longer than 20 minutes.

The CCW system is also designed to remove heat during normal operation from the CFCUs, ESF pump coolers, and various non-essential heat loads. The CCW system includes three pumps (BI)(P), two heat exchangers, two vital headers and one non- l vital neader. The heat transferred to the CCW system is transferred to the ASW system through the two heat exchangers.

Following an accident, the temperature of the CCW system is primarily a function of heat input to the system from the CFCUs  ;

and RHR heat exchangers (during recirculation), and heat removal from the system by the ASW system.

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2. Biological Fouling and Scaling Biological fouling consists of two main components, microfouling and macrofouling.

acrofouling is the blockage of flow through the heat exchanger ,

tubes due to mussels and barnacles or other foreign materials in the seawater environment. Blocked tubes reduce heat transfer.

capability by reducing the effective surface area. ,

Microfouling includes both organic and inorganic materials that .i adhere to the ASW heat exchanger tubes and, by their presence,  !

degrace heat transfer at the tube surface. Scaling is related to the operation of the cathodic protection system. Calcium ,

carbonate can be expected to plate out on the inside surface 3 near the end of the tubes. Since the calcium carbonate deposit is a thin layer and the affected area is small, the overall-  !

1mpact of calcification on the heat transfer capability is small. ,

C. Event

Description:

1. Previous Reportable Events on ASW system In LER l-84-040. submitted March 24, 1989, PG&E reported that engineering recommendations for plant operation to assure compliance with the design bases for the CCW system and the ASW ,

system were not incorporated in plant procedures and emergency proteouros. Emergency Operating Proceoure (EOP) E-0. " Reactor Trip on Safety injection," was revised to add a new step to verify that both ASW pumps start following a safety injection.

If only one pump starts, the operator is instructed to place the secono CCW heat exchanger-in service. ,

In LER l-91-018, submitted January 17, 1992, PG&E determined that the heat load on the'CCW system during the cold-leg ,

recirculation phase following a LOCA could potentially exceed the CCW system design basis temperature limits. Because the injection phase had previously been considered the limiting case.

for CCW temperature, this condition was considered to be outside the design basis of the CCW system. E0P E-1.3, " Transfer to Cold Leg Recirculation," was revised to require reducing CFCU and RHR heat. loads if two ASW pumps and two CCW heat'exchangers are not operating.

2. Heat Exchanger Reevaluation  ;

in response to GL 89-13, PG&E performed testing of the Units 1 and 2 CCW heat exchangers in February 1991 and September 1991, respectively. Based on engineering ~ judgement at the time, PG&E

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mncluded that the testing adequately demonstrated that the CCW I heat exchangers met design basis requirements. j A;0A surveillance report of the ASW system, issued July 28, i 1993, identified a concern regarding the ability of the ASW  !

system to satisfy its design basis heat removal requirements  !

with_the CCW heat exchanger (s)'in the fouled condition  :'

carresponding to a differential pressure (dp) of 140 inches of wter.

Am NRC inspection performed in December 1993 (Inspection Report  !

SD-275/323-93-36) identified a concern with the basis for the .;

gerability of the ASW system with regard to CCW heat exchanger  !

recrofouling, microfouling, and tube plugging.  !

In response to those concerns, PG&E initiated a Technical Review '

Group (TRG) to perform a comprehensive evaluation of the present  !

and past capability of the ASW system to meet its design basis. i The.following is a summary of the results of the investigation of the parameters affecting ASW system operability. Detailed risults of the investigation cre discussed in PGLE Letter No. DCL-94-037_(February 15, 1994). l l

3. Operability Parameters l

a. Biological Controls on the ASW System DCPP has implemented chlorination to control both micro-and macrofouling. Batch chlorination was in use at DCPP i from late-1984 through 1991', althougn a few periods existed during this timeframe when equipment problems or system enhancement modifications precluded the use of chlorination. Since 1992, the method used has been-continuous chlorination. Both methods of chlorination can control the growth of macrofouling as well as microfouling, although continuous chlorination is a superior method. The control of macrofouling requires higher chlorine concentrations than the control of microfouling; however, DCPP maintains sufficient chlorine in the ASW system to control both types of biofouling in the piping and the heat exchangers.

On August 23, 1990, microfouling samples were taken from CCW 1-2 heat exchanger. Biofouling was noted on the waterbox walls'and along the interior surfaces of the  ;

individual tubes. This was an unusual circumstance since  !'

appreciable microfouling in the four CCW heat exchangers had not been found in previous CCW heat exchanger inspections. CCW 1-1 heat exchanger was inspected September 5, 1990, and no biofouling builduo was noted.

In response to the observations noted in CCW 1-2 heat 1 1

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exchanger, daily chlorine injections were made for two weeks following the inspection.

In 1992 continuous chlorination of the ASW system was implemented as follows:

e January 1992 ASW line 1-1 e March 1992 ASW line 2-1

• September 1992 ASW line 1-2 e Novemoer 1992 ASW line 2-2

b. Maintenance Practices Cleaning of heat exchangers during operation is periodically performed to remove debris such as mussels, barnacles, shells, or other debris that is obstructing flow (macrofouling). As discussed below, during '

operation, differential pressure (dp) is used as a threshold indicator to determine when cleaning is required. In addition, based on an inspection of the heat exchanger during the cleaning activities, waterjetting may also be performed if necessary to remove accumulated biofouling.

In accordance with Maintenance Procedure MP M-56.16, " Heat Exchanger Tube Cleaning," the heat exchanger tubes are mechanically scraped during each refueling outage (nominally every 18 months: ref. Recurring Task Numbers 51872, 551872. 53587, and 551886). Cleaning of the tubes with a waterjet has been performed periodically in the past during macrofouling cleaning (whenever the dp reaches its administrative limit).

c. CCW Heat Exchanger Differential Pressure Continuous monitoring of the dp across the heat exchanger is a diagnostic tool and cannot, by itself, quantitatively be used to determine operability. However, it can be used as a threshold indicator to assess the heat exchanger condition during operation. Differential pressure is monitored by taking shift readings of dp, as well as by a dp alarm in.the control room. Differential pressure provides an indication of the heat exchanger condition and is used to determine when'the heat exchanger should be cleaned. Differential pressure provides an indication of the heat exchanger condition that is qualitatively linked to each heat exchanger's heat transfer capability.

Although the measured dp across the heat exchanger does not provide an all-inclusive indicator of heat exchanger performance, it does give a general indication of the

' combined effect of macrofouling and heavy scaling.

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. Therefore, the dp measurement, with microfouling under control, is one indicator of overall heat exchanger functionality. Maintenance, surveillance testing, and inspections during cleanings are also other indicators.

Mechanical cleaning of the heat exchangers every outage, and continuous chlorination and periodic waterjetting during operation minimizes microfouling and scaling.

Therefore, differential pressure is a reasonable indicator of overall heat exchanger functionality.

The dp setpoint from plant startup until January 1986 was 110 inches. which resulted in a standing alarm. From January 1986 until April 1988, the op setpoint was 170 incnes. From April 1988 until September 1989, the dp setroint was 167 inches. From Septemoer 1989 until Ncvember 1989, the setpoint was 120 inches. The current setpoint of 140 inches was initiated in Novemoer 1989.

Based on a review of the above macrofouling information, it was determined that the limiting comoination of macrofouling and high ocean temperature occurreo on November 8, 1987.

d. Operational Controls As discussed above, PG&E enhanced its emergency procedures in February 1989 to place a second CCW heat excnanger in I

service if both ASW pumos fail to start following an j accident. The emergency procedures were further enhanceo in 1991 to include directions regaroing eouipment configurations to control CCW temperature during l recirculation. '

4. Heat Exchanger Performance Testing On February 2, 1991, in response to the requirements of GL 89-13, PG&E performed testing of the Unit 1 CCW heat exchangers to verify their capability to meet design basis (nameplate) heat removal requirements.  !

The performance results were:

COMPONENT HEAT EXCHANGE RATIO CCW HX l-1 1.080 CCW HX l-2 0.987 On September 1, 1991, PG&E performed testing of the Unit 2 CCW heat exchangers. The performance results were:

COMPONENT HEAT EXCHANGE PATIO CCW HX 2-1 1.112 CCW HX 2-2 1.109 l

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further evaluation of the test results, PG&E now concludes that the CCW 1-2 heat exchanger testing results (which were evaluated using '

Heat Transfer Consultants, Inc.'s HTC-STX computer model) did not meet the design basis. However, PGLE requested HOLTEC, International to analyze the GL 89-13 test data for the CCW 1-2 heat exchanger. The e HOLTEC model was specifically developed for GL 89-13 evaluation and  !

l has been widely used by the nuclear power industry. It has been validated using an approved software quality assurance program and has  ;

been used in audit responses; therefore, it is considered a good  ;

validation of the HTC-STX program. The results of the HOLTEC model i reanalysis of the GL 89-13 test data predicted that the CCW 1-2 heat  ;

exchanger performance at nameplate condition would be 101 percent with i a 95 percent confidence level.

5. Conclusion )

On Decemoer 30. 1993, at 1150 PST, with Unit 1 in Mode 3 (Hot Standby) at 0 percent power and Unit 2 in Mode 1 (Power Operation) at 100 percent power, PG&E determined that the CCW heat exchangers for both units may have not met their design basis prior to implementation of' continuous enlorination. This condition was reported to the NRC as a one-hour, non-emergency report in accordance with 10 CFR 50.72 (b)(1)(ii)(B) at 1150 PST on December 30, 1993. Continuous chlorination was fully implemented in September and Novemoer 1992 for Units 1 and 2, respectfully.

The continuing investigation reviewed the current maintenance, operational and testing practices. The maintenance practices that provide assurance that the heat exchangers will remain sufficiently clean of biofouling include continuous chlorination, scraping of the tubes during refueling outages, cleaning of the tubes and tubesheet when the measured dp is 130 inches of water, and declaring the heat exchanger inoperaole at 140 inches of water.

The review of historical information determined that a combination of three factors led to the microfouling growth discovered in CCW 1-2 heat exchanger in August 1990. Chlorination was not performed for a period of approximately six months prior to the Unit 1 heat exchanger-inspections. During this period, the gaseous chlorine system was out =

of service for replacement of cast' iron piping. Concurrent with the absence of chlorine, the following unusual environmental conditions contributed to the microfouling:  !

• Beginning in March 1990 and continuing through June, coastal upwelling was experienced. This upwelling increased the nutrient level of the ocean surface waters.

• The high nutrient level, when combined with the rising ambient ocean temperature in July and August, and the absence of

LICENSEE EVENT REPORT (LER) TEXT CCJNTINUATION patJLITY %4mt gi) DOCKET N M ER (2) .fB 4789 f t (8t s s a r,( t vtaa uo6nstem DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 93 -

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chlorine injection, produced ideal conditions for microfouling organisms such as bacteria, diatoms, and filamentous algae.

• CCW 1-2 heat exchanger was the only CCW heat exchanger that was not waterjetted or scraped within seven months prior to conducting the performance test.

In summary, PG&E's review of the operating history of the CCW heat exchangers from plant startup to date resulted in further review of the following periods for potential safety significance:

• Current ASW system condition (after full implementation of continuous chlorination in Novemoer 1992).

• System condition between August 1990 and February 1991.

• Operation between August 1986 and March 1988 (operation with a dp setpoint alarm of 170 incnes).

D. Inoperable Structures, Components, or Systems that Contributed to the Event:

Chlorination was not performed for a six-month period of time in 1990 due to the replacement of cast iron piping in the chlorination and associated systems.

E. Dates and Approximate Times for Major Occurrences:

! 1. July 18, 1989: Generic Letter 89-13 was issued.

1

2. August 23, 1990: Samples taken from CCW 1-2 heat exchanger, indicating excessive microfouling.

3. February 1991: Unit 1 GL 89-13 heat exchanger  ;

testing. l

4. September 1991: Unit 2 GL 89-13 heat exchanger testing.  ;

l

5. November 1992: Continuous chlorination fully l implemented for ASW system. <

6. July 28, 1993: QA surveillance report issued.

7. December 30, 1993: Event / Discovery date. PG&E determined that CCW 1-2 heat exchanger may have had sufficient microfouling to preclude the CCW i l

. , .. l l

LICENbcE EVENT REPORT (LER) TEXT CCmTINUATION unan w m mn mu m u +, n < . , . ..w< I j

1 rot im DIABLO CANYON UNIT 1 015 l 0 l 0l 0 l 2 l 7 l 5 93 -

0l 1l 2 -

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system from meeting its design basis on August 23, 1990.

F. Other Systems or Secondary Functions Affected:

None. l G. Method of Discovery:

i' During a TRG evaluation of an engineering reanalysis, PG&E determined that CCW 1-2 heat exchanger may have had sufficient fouling to have ,

precluded the CCW system from meeting its design basis on  !

August 23, 1990.

H. Operators Actions:

None required.

1. Safety System Responses:

None required. I III. Cause of the Event i

A. Immediate Cause: l l

Fouling. l l

B. Root Cause: I i

The root cause of this event is an inadequate understanding of the )

effects of fouling on the CCW heat excnangers, j i

C. Contributing Cause: ,

l

1. Chlorination frequency. l l

2. Mechanical cleaning frequency.

IV. Analysis of the Event l

The key parameters affecting the performance of the ASW and CCW systems j include: macrofouling and microfouling, ASW flow, and ocean temperature.

An extensive review of historical maintenance, testing, operational, and  ;

biological factors was performed to identify time periods with a high i potential for macrofouling and microfouling. During this review of past i operation, specific periods of time have been identified during which one or l more of these key parameters may have been outside current acceptance .

criteria. These time periods, and the safety significance of the associated fouling, are discussed below. '

.f a LICENSEE EVENT REPORT (LER) TEXT CONTINUATION r a:I L I * ' *AM (1) DOCKET wJMSER (2) .ta armenge est serg vtaa i seemn DIABLO CANYON UNIT 1 0I5l0l0l0!21715 93 -

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Oll 10 I" Ygsf *)

Biological Fouling Conditions The potential for significant microfouling of CCW heat exchanger tubes occurs when certain conditions are met. These conditions include:

• An upwelling of cold, nutrient-rich water from deep ocean layers, which occurs as a result of strong northwesterly winds. that characteristically blow during the spring.

e A period of high ocean temperatures, which, following an upwelling period, allows the microorganisms to " bloom." Experience indicates that ocean temperatures of approximately 58'F or greater must be reached over a several week period for the " bloom" to occur.

e The cnlorination system is out-of-service for a considerable period l prior to ano during the " bloom." Without chlorination during the l

" bloom" period, m1crofouling could form on the tubes of the heat exchanger. If cnlorination is restarted after the " bloom" has )

occurreo, further microfouling is stopped. However, residual material placed by the microorganisms remains in the tubes as a coating and continues to impact heat exchanger performance. Once deposited, i waterjetting or scraping of the tubes is needed to remove the residual  ;

material. l Bounding Microfouling Condition PG&E's evaluation of maintenance and operational practices over Diablo Canyon's operating history indicates that the bounoing conditions for potentially significant microfouling only occurred during August 1990. l Prior to this period, upwelling of nutrients had occurred ano was followee l

i by a period of ocean warming. As a result, a microfouling " bloom" occurred.

PG&E's analysis indicates that microfouling reached significant levels in August 1990 as ocean temoerature exceeded 58'F. In addition, the chlorination system was out-of-service during this period while PG&E was l replacing cast iron piping in the system. When batch chlorination was restored on August 21, 1990, further microfouling ceased. However, the residual material from the microorganisms remained in the CCW heat exchanger tubes until waterjetting or tube scraping was performed. PG&E's review indicates that there were no other time periods when the lack of chlorination and maintenance was coupled with favorable environmental conditions for microfouling.

Of the four CCW heat exchangers, the 1-2 heat exchanger was the most susceptible to microfouling based on its chlorination, maintenance, and operating history. The remaining three heat exchangers received waterjet cleanings between the period of high microfouling potential and the performance of the GL 89-13 performance testing. In addition, two of the other three heat exchangers were operated less frequently during the period of high microfouling potential.

a +

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FAC;g !, namt (1) QOC K E T hih*0 E R (2) Y a er a y e ess , ,,g "T1 l O DIABLO CANYON UNIT 1 0l5lOl0l012l715 93 -

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The CCW 1-2 heat exchanger was not waterjetted or scraped during the period from August 1990 until after the performance of the GL 89-13 performance test in February 1991. However, as discussed above, batch chlorination was resumed on August 21, 1990, and PG&E's reanalysis of the February 1991 CCW 1-2 heat exchanger performance test using a certified test model indicates that the CCW 1-2 heat exchanger met its design basis (nameplate) heat removal capacity at that time. PG&E believes that the heat transfer microfouling characteristics of the CCW 1-2 heat exchanger during its associated GL 89-13 testing represent the bounding microfouling case.

PG&E evaluated the highest macrofouling that may have existed coincident with high microfouling. During August 1990, the CCW 1-2 heat exchanger was taken out of service for cleaning. It was not again taken out of service until the test in February 1991, at which time the dp was about 110 inches.

The August 1990 do of about 130 inches represented the highest macrofouling reacheo during this bounding microfouling period. The level of macrofouling associated with a op of 130 inches, coupled with an assumed level of microfouling found during the testing of the CCW 1-2 heat exchanger, represents the most limiting fouling of a CCW heat exchanger.

Bounding Macrofouling Condition PG&E's review of macrofouling data identified periods of operation at an elevated dp (greater than 140 inches). The historical data focused attention on a period from August 1986 to March 1988 during which, on three occasions, the combination of recorded dp and actual ASW temperatures indicated the potential for excessive macrofouling. The apparent bounding case of macrofouling identified in this period occurred on Novemoer 8, 1987, wnen CCW 1-2 heat exchanger was removed from service with a op of about 170 incnes in conjunction with an ocean water daily mean temperature of 59.9 F. A review of environmental conditions associated with this period of high do determined that coincident conditions required for significant microfouling did not exist. PG&E believes that microfouling levels at that time were consistent with the low levels observed during the Unit 2 CCW heat exchanger GL 89-13 tests.

Safety Significance PG&E has analyzed the bounding cases of heat exchanger fouling for safety significance. These analyses were performed using the mass and energy (M&E) release model that is the licensing basis for DCPP.

The impact of bounding fouling cases on the containment integrity analyses was performed by Westinghouse. Westinghouse evaluated the design basis LOCA, as well as the limiting MSLB accidents for impacts on containment pressure and temperature. The conclusion of these evaluations is that the containment design basis pressure and temperature would not have been exceeded during a postulated LOCA or MSLB.

The design basis CCW temperature limits allow a transient temperature maximum of 132* F for 20 minutes. The temperature limit for continuous

. LICENSEE EVENT REPORT (LER) TEXT CONTINUATION unun . m mur m a . mn . . , . ...,

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i

{. operation is 120* F. PG&E has evaluated the impact of the bounding fouling ,

L cases on the limiting post-LOCA CCW temperature transients. Using the l current licensing basis M&E release model, PG&E and Westinghouse have l determined that the peak CCW temperature would have remained within the H design basis CCW temperature limits during the injection phase following a

^

LOCA. The containment conditions calculated by Westinghouse were then used by PG&E to evaluate the CCW temperature transient that would result during the recirculation phase. These evaluations concluded that the CCW l temperature could have exceeded its design basis temperature limits in recirculation for an extended period if operator action is not taken.

The potential for the CCW system to overheat during the post-LOCA recirculation pnase of an accident was previously identified by PG&E in 1991. LER l-91-018, " Component Cooling Water System Outside Design Basis,"

reported that the heat load during cold leg re:irculation may exceed the CCW.

system design basis temperature limits. Specific recirculation transient analyses were not performed. At that time, it was reported that operator l

action to keep CCW temperatures within design limits was required if the two ASW punip/two CCW heat exchanger configuration could not be established. In response to the LER, guidance to address conditions when both ASW pumps and both CCW heat exchangers were not available was incorporated into step 3.d of E0P E-1.3 in 1991. The potential for elevated CCW temperatures identified in the bounding fouling cases above is due primarily to the heat loads imposed on the system during recirculation, and not specifically caused by the identified heat exchanger fouling. Calculations indicate

.that, had the 1991 E0P guidance been in place at the time that the bounding conditions existed, the CCW system temperature would have remained within its design basis.  !

l To bound the conditions in place during the 1990 high macro- and l microfouling case, as well as the 1987 high macrofouling case, PG&E l evaluated the CCW temperature transient assuming the likely operator actions {

Prior to the 1991 revision of E0P E-1.3, E0P E-0 was for each period.

revised in 1989 to require placing a second CCW heat exchanger in service when only one ASW pump is available (post-LOCA). Because of the enhanced procedural guidance available to the operators in 1990, the timeline for the period of high microfouling had the operators align the second heat exchanger within 20 minutes following the initiation of the LOCA (This is consistent with operator action described in SSER 16.). A different 3 timeline was used for the period of high macrofouling as this case preceded the 1989 E0P changes. While not formally proceduralized, operator actions believed to be representative of those actions that would have occurred prior to the 1989 E0P changes were used. The timeline would have operators secure two CFCUs 15 minutes after the start of recirculation in response to high CCW temperature alarms and subsequently place the second CCW heat exchanger into service 10 minutes later.

Assuming operator action as described above, the limiting CCW temperature transients were evaluated. The peak CCW temperature for the high macro- and microfouling case was approximately 139'F, and the cumulative time above 120*F was approximately 30 minutes. The peak CCW temperature for the high -

LICENScE EVENT REPORT (LER) TEXT CCMTINUATION

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e macrofouling period was approximately 136*F, and the cumulative time above 120*F was approximately 34 minutes. The impact of the elevated CCW temperatures on the components of the vital CCW headers was evaluated.

Westinghouse analyzed the impact of the CCW temperature profile and has determined that the SI and RHR pumps and the CFCU fan motors would perform their design basis function. The CCW rump manufacturer confirmed that the CCW pumps would perform their design basis function at the elevated CCW temperatures. The post-LOCA sampling system may have been temporarily disabled by the elevated CCW temperatures. However, the ability to assess core damage remained available from alternate proceduralized means. The centrifugal charging pumps (CCPs) cannot be shown to continue to be available at these elevated temperatures, although the exact point of failure is not known. However, the CCPs are available for the entire injection phase of the accident. Regaroless of the availability of the CCPs for the rec 1rculation phase, Westinghouse and PG&E analyses have determined that during the recirculation phase, other ECCS pumps are available to perform required ECCS functions.

Based on the foregoing detailed analysis of this event, PG&E concludes the following:

e The fouling identified on the CCW heat exchangers would not have resulted in the containment design pressure or temperature being ,

exceeded.

e The CCW design basis temperature limits would only have been exceeded i during post-LOCA recirculation. I e All vital components served by the CCW system would have continued to perform their design basis function, or redundant equipment would have i been available to perform these functions. l Accordingly, this event had no safety significance and the health and safety of the public would not have been affected.

V. Corrective Actions A. Immediate Corrective Actions:

1. An operations standing order was prepared to notify the system engineer if the ASW chlorination system becomes inoperable. This will provide assurance that the 1

- chlorination system is returned to service quickly enough to 1 prevent excessive CCW heat exchanger microfouling.

2. An operations standing order was prepared to ensure that the CCW heat exchangers are cleaned when the dp reaches 130 inches. In addition, the associated ASW train will be .

declared inoperable whenever the dp reaches 140 inches.

This stancing order is applicable for an operating I

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION

%e-m ma n - . m a. - ,. , , , ..

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y 3 DIABLO CANYON UNIT 1 un .n 0l 5l 0 ! 0l 0l 2 l 7 I 5 93 .

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0l1 14 l" configuration of on2 ASW pump running with one CCW HX aligned.

3. STP I-1A, " Routine Shift Checks Required by Licenses," has been revised to require that the CCW heat exchanger dp be verified to be less than 140 inches of water. This revision will incorporate the existing standing order to begin preparations to clean the heat exchangers at 130 inches.

B. Corrective Actions to Prevent Recurrence:

1. The continuous chlorination program for the ASW system has-been fully implemented. ASW system continuous enlar1 nation effectively controls the effects of biofouling.

2. In addition to inspections performed when dp limits are reached, a recurring task work order will be initiated to assure that each heat exchanger will be inspected at a frequency of six months and cleaned as required.

3. Additional CCW heat exchanger performance tests on both units will be performed to verify the adequacy of operational and maintenance practices to assure that the CCW heat exchangers meet design basis requirements. The tests will be conducted during the IR6 and 2R6 refueling outages and will include dp measurement. Upon completion of additional heat exchanger performance tests scheduled for 1R6 and 2R6, PG&E will reevaluate the op setpoint.

4 Enhanced ASW flow instrumentation will be installed with local readouts.

5. ECG 17.2 has been approved to provide administrative controls on the ASW chlorination system. This ECG will document compensating actions to be taken if the ASW l chlorination system is inoperable for greater than 14 days.

l

6. PG&E agrees that trending of the dp increase on each CCW heat exchanger would be useful in anticipating calcification and other buildup that may affect dp. Consequently, PG&E will revise STP M-26 to require a formal trending program to monitor this parameter.

7. An Integrated Problem Response Team (IPRT) will be conducted on the ASW, CCW, and interfacing systems by the end of 1994.

This IPRT will thoroughly and critically review these ]

systems. Membership of the IPRT will include operations,  ;

quality services, maintenance, Westinghouse, and engineering personnel. Based on the results of the IPRT, DCM S-17B will j

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION raau" - m man mo m a ,,-.,, i ...

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DIABLO CANYON UNIT 1 Ol 5l 0l 0l 0l 2 l 7 l 5 93 -

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be revised to provide additional information on ASW system l heat removal capacity. I VI. Additional Information l

A. Failed Components:  !

None.

1 B. Previous LERs on Similar Problems:

1. LER l-91-018-01, " Component Cooling Water System Outside Design Basis Due to Personnel Error."

PG&E determined that the heat load on the CCW system during the cold-leg recirculation phase following a LOCA could potentially exceed the CCW system design basis temperature limits. Because the injection phase had previously been considered the limiting case for CCW temperature, this condition was considered to be outside the design basis of the CCW system. The root cause was attributed to personnel error. The corrective actions to prevent recurrence included additional training for design engineers to emphasize that data known to be conservative for one application may be nonconservative for another application.

Because this event did not address the potential for biofouling of heat exchangers, the corrective actions taken would not have prevented the current event.

2. LER l-84-040, "CCW and ASW System Design Basis Recuirements Not Incorporated into Plant Procedures Due to Inadequate Tracking of Resolution from Correspondence and Communication."

Engineering recommendations for plant operation to assure compliance with the design basis for the CCW and ASW systems were not incorporated in plant procedures. Since this event involved incorporation of design constraints in plant procedures, corrective actions taken to prevent recurrence could not have prevented the current event since they would not affect biofouling in the CCW heat exchangers.

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4 ATTAC.HMENT 5

Pacific Gas scd Electric Congsny

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1 P: .: : C:, Emr 3 r r y v r a:er 415 373 4664

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5 973 2313 May 27,1994 PG&E Letter DCL-94120 RECEIVED '

U.S. Nuclear Regulatory Commission JUN - 71994 ATTN: Document Control Desk CHRISTOPHER J. WARNER Washington, D.C. 20555 i

Docket No. 50-275, OL-DPR 80 j Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Licensee Event Reoort 1 93 012-02 Auxiliary Saltwater System Outside Desian Basis Due to Foulina l l

Gentlemen:

I Pursuant to 10 CFR 50.73(a)(2)(ii)(B), PG&E is submitting the enclosed revision to Licensee Event Report 1-93-012 concerning the auxiliary saltwater (ASW) system being outside its design basis due to fouling. This revision is being submitted to report the results of additional testing performed on the component cooling water (CCW) heat exchangers during the Unit 1 sixth refueling outage.

PG&E's comprehensive evaluatioh concluded that this event had no safety significance and that the health and safety of the public were not affected.

Sincerely, iA& M Gregary M. Rueger 1 i

l cc: L. J. Callan I Mary H. Miller f

Kenneth E. Perkins Sheri R. Peterson Diablo Distribution INPO DCO-93 EN-N022 Enclosure 6475S/DPS/2246

LICENSEE EVENT REPORT (LER) 220323 DOCEtT NUMBER (21 PAGE(3, F ACluf f N AME (1)

DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 1 l 'l 16 mtz m AUXILIARY SALTWATER SYSTEM OUTSIDE DESIGN BASIS DUE TO FOULING EVENT DATE f 68 LER Nuwssp les REPOmf DATE (71 OTM(a F ACIL1TlES INVOLVED (3)

MO30 DAY YR YM SEO TIAL REVI ON Moss DAY YM DOCKET huMast tsp 0 0 0 3 2 3 DIABLO CANYON UNIT 2 12 30 93 93 -

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0l2 Tais arpoor is seemstfro PvasuANT to Tat accusatMENYs or lo Cra 05 27 94 (11) 0 5 0 0 0 c.

egaaf 3

ot7ct W 10 CFR 50. 73( a)( 2)( i i )(6 )

"" OTrER -

0l 0l 0 (Specify in Abstract below and in text, i.R C Form 366A)

UCENSEE CONT ACT FOR THis LER 112 eteo 0%r % was o

^" (

• DAVID P. SISK - SENIOR REGULATORY COMPLIANCE ENGINEER 805 545-4420 COMPLETI OhE UNE FOR E.ACH COMPONENT F AJLURE DESCRISED IN THl$ REPORT {13)

C A./ ht SYSTEM CJ4POh(N T MAN FAC. a O E CAv5E 575 FEM C'.MPON L M I MAN FA e a(PC A (

l l ll l l l l lll ll l l lll III I III III " "'" D *"

svPmMantat McPoRr taPactsD tie' EXPECTED SUBMISSION l l l YES (if yes, Conclet e EXPECTED SUBMIS$10N DATE) lX l NO 1

40stAACI (18) -l l

On December 30, 1993, at 1150 PST, with Unit 1 in Mode 3 (Hot Standby) at 0 percent power and Unit 2 in Mode 1 (Power Operation) at 100 percent power, PG&E determined that the auxiliary saltwater (ASW) system and its associated component cooling water (CCW) heat exchangers for both units may not have met their design basis for certain time periods prior to implementation of continuous chlorination.

Continuous chlorination was fully implemented in September and November 1992 for l Units I and 2, respectively. This condition was reported to the NRC as a one-hour, non-emergency report in accordance with 10 CFR 50.72 (b)(1)(ii)(B) at 1150 PST on December 30, 1993.

The cause of this condition was an inadequate understanding of the effects of fouling on the CCW heat exchangers.

The ASW systems for both units currently are operable given the present l maintenance, operational, and testing activities. These activities assure that  !

the ASW system will remain sufficiently clean such that fouling will not prevent the system from performing its design basis functions. CCW heat exchanger tests on both units will be performed to provide additional confirmation of the adequacy of operational and maintenance practices to assure that the CCW heat exchangers meet their design basis requirements. An equipment control guideline was implemented to ensure compensating actions are taken if the ASW chlorination system becomes inoperable, wtsm -. -

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 220923

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0l1 2l'l16 TOT (17) l 1. Plant Conditions Unit 1 and Unit 2 operated in various modes at various power levels while this condition existed.

II. Descriotion of Event A. Summary:

On December 30, 1993, at 1150 PST, with Unit 1 in Mode 3 (Hot Standby) at 0 percent power and Unit 2 in Mode 1 (Power Operation) at 100 percent power, PG&E determined that the auxiliary saltwater (ASW) system (BI) and its associated component cooling water (CCW) heat exchangers (BI)(HX) for both units may not have met their design basis requirements for certain time periods prior to implementation of continuous chlorination. Continuous chlorination was fully implemented in September and November 1992 for Units 1 and 2, respectively. This condition was reported to the NRC as a one-hour, non-emergency report in accordance with 10 CFR 50.72 (b)(1)(ii)(B) at 1150 PST on December 30, 1993.

1

8.

Background:

l

1. Design .

1 Following a loss of coolant accident (LOCA) or a main steam line break (MSLB) inside containment, the CCW system is required to provide cooling water to the containment fan cooling units (CFCus) (BK)(FAN) for containment heat removal, and to the various engineered safeguards features (ESF) pump coolers.

During the recirculation phase of the LOCA, the CCW system also cools the residual heat removal (RHR) heat exchangers (BP)(HX).

In order for the CCW system to perform its function, CCW water temperature must remain at or below 120*F for continuous operation and may exceed 120 F, up to a maximum of 132*F, for no longer than 20 minutes. j The CCW system is also designed to remove heat during normal operation from the CFCUs, ESF pump coolers, and various non-essential heat loads. The CCW system includes three pumps (BI)(P), two heat exchangers, two vital headers and one non-vital header. The heat transferred to the CCW system is transferred to the ASW system through the two heat exchangers.

Following an accident, the temperature of the CCW system is primarily a function of heat input to the system from the CFCUs and RHR heat exchangers (during recirculation), and heat removal from the system by the ASW system.

64755

I 1

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FAC]d ly NAM ( {}J DOCKET h psEn (2) t r a hwM a (s) 220923paGE its "O" "a"," i DIABLO CANYOil UNIT 1 0! 5l 0l 0l 0l 2 l 7 l 5 93 -

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0l1 3 \"l 16 l TEAT (27)

2. Biological Fouling and Scaling i

Biological fouling consists of two main components, microfouling and macrofouling.

Macrofouling is the blockage of flow through the heat exchanger  :

tubes due to mussels and barnacles or other foreign materials in the seawater environment. Blocked tubes reduce heat transfer capability by reducing the effective surface area.

Microfouling includes both organic and inorganic materials that ,

adhere to the ASW heat exchanger tubes and, by their presence, degrade heat transfer at the tube surface. Scaling is related to the operation of the cathodic protection system. Calcium carbonate can be expected to plate out on the inside surface near the end of the tubes. Since the calcium carbonate deposit is a thin layer and the affected area is small, the overall

. impact of calcification on the heat transfer capability is small.

C. Event

Description:

1. Previous Reportable Events on ASW system In LER 1-84-040, submitted March 24, 1989, PG&E reported that engineering recommendations for plant operation to assure compliance with the design bases for the CCW system and the ASW ,

system were not incorporated in plant procedures and emergency 1 procedures. Emergency Operating Procedure (EOP) E-0, " Reactor Trip on Safety Injection," was revised to add a new step to verify that both ASW pumps start following.a safety injection.

If only one pump starts, the operator is instructed to place the second CCW heat exchanger in service.

In LER 1-91-018, submitted January 17, 1992, PG&E determined that the heat load on the CCW system during the cold-leg i recirculation phase following a LOCA could potentially exceed the CCW system design basis temperature limits. Because the injection phase had previously been considered the limiting case for CCW temperature, this condition was considered to be outside the design basis of the CCW system. E0P E-1.3, " Transfer to Cold Leg Recirculation," was revised to require reducing CFCU and RHR heat loads if two ASW pumps and two CCW heat exchangers are not operating.

6475F

I LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 220923

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2. Heat Exchanger Reevaluation In response to GL 89-13, PG&E performed testing of the Units 1 and 2 CCW heat exchangers in February 1991 and September 1991, respectively. Based on engineering judgement at the time, PG&E concluded that the testing adequately demonstrated that the CCW ,

heat exchangers met design basis requirements. '

A QA surveillance report of the ASW system, issued July 28, 1993, identified a concern regarding the ability of the ASW i system to satisfy its design basis heat removal requirements i with the CCW heat exchanger (s) in the fouled condition '

corresponding to a differential pressure (dp) of 140 inches of water.

An NRC inspection performed in December 1993 (Inspection Report 50-275/323-93-36) identified a concern with the basis for the operability of the ASW system with regard to CCW heat exchanger macrofouling, microfouling, and tube plugging.

In response to those concerns, PG&E initiated a Technical Review Group (TRG) to perform a comprehensive evaluation of the present and past capability of_the ASW system to meet its design basis. l The following is a summary of the results of the investigation  !

of the parameters affecting ASW system operability. Detailed l results of the investigation are discussed in PG&E Letter i No. DCL-94-037 (February 15, 1994).

1

3. Operability Parameters I

a. Biological Controls on the ASW System ,

1 DCPP has implemented chlorination to control both micro-and macrofouling. Batch chlorination was in use at DCPP from late-1984 through 1991, although a few periods

.i existed during this timeframe when equipment problems or

! system enhancement modifications precluded the use of chlorination. Since 1992, the method used has been continuous chlorination. Both methods of chlorination can a control the growth of macrofouling as well as i

microfouling, although continuous chlorination is a superior method. The control of macrofouling requires higher chlorine concentrations than the control of microfouling; however, DCPP maintains sufficient chlorine in the ASW system to control both types of biofouling in the piping and the heat exchangers.

i f

64755  !

i i

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 220323 F ALILJ T T 9eAP4( (1) DOCat! WJM6(R (2) L(9 MJMBER t6) c a e,( ep viAn ss wrm arv DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 93 -

0l 1l 2 -

0l1 5 l 'l 16 TEAf (17)

On August 23, 1990, microfouling samples were taken from CCW 1-2 heat exchanger. Biofouling was noted on the waterbox walls and along the interior surfaces of the individual tubes. This was an unusual circumstance since appreciable microfouling in the four CCW heat exchangers had not been found in previous CCW heat exchanger inspections. CCW 1-1 heat exchanger was inspected September 5, 1990, and no biofouling buildup was noted.

In response to the observations noted in CCW 1-2 heat exchanger, daily chlorine injections were made for two weeks following the inspection.

In 1992 continuous chlorination of the ASW system was implemented as follows:

e January 1992 ASW line 1-1 e March 1992 ASW line 2-1 e September 1992 ASW line 1-2 e November 1992 ASW line 2-2

b. Maintenance Practices cleaning of heat exchangers during operation is periodically performed to remove debris such as mussels, barnacles, shells, or other debris that is obstructing 3 flow (macrofouling). As discussed below, during i operation, differential pressure (dp) is used as a threshold indicator to determine when cleaning is I required. In addition, based on an inspection of the heat l exchanger during the cleaning activities, waterjetting may also be performed if necessary to remove accumulated biofouling.

In accordance with Maintenance Procedure MP M-56.16, " Heat Exchanger Tube Cleaning," the heat exchanger tubes are mechanically scraped during each refueling outage (nominally every 18 months: ref. Recurring Task Numbers 51872, 551872, 53587, and 551886). Cleaning of the tubes with a waterjet has been performed periodically in the past during macrofouling cleaning (whenever the dp reaches its administrative limit).

c. CCW Heat Exchanger Differential Pressure Continuous monitoring of the dp across the heat exchanger is a diagnostic tool and cannot, by itself, quantitatively be used to determine operability. However, it can be used as a threshold indicator to assess the heat exchanger 64755

)

a

i LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 220923

.m a , , -, m =cui -na m

, u .;,- . + _

.m,,,

DIABLO CANYON UNIT 1 0l 5l 0l 0l 0l 2 l 7l 5 93 -

0l1l2 -

Oll 6 l"l 16 fini (17) condition during operation. Differential pressure is monitored by taking shift readings of dp, as well as by a dp alarm in the control room. Differential pressure' provides an indication of the heat exchanger condition and is used to determine when the heat exchanger should be cleaned. Differential pressure provides an indication of the heat exchanger condition that is qualitatively linked to each heat exchanger's heat transfer capability.

Although the measured dp across the heat exchanger does not provide an all-inclusive indicator of heat exchanger performance, it does give a general indication of the combined effect of macrofouling and heavy scaling.

Therefore, the dp measurement, with microfouling under l

control, is one indicator of overall heat exchanger functionality. Maintenance, surveillance testing, and inspections during cleanings are also other indicators.

Mechanical cleaning of the heat exchangers every outage, and continuous chlorination and periodic waterjetting l

during operation minimizes microfouling and scaling.

Therefore, differential pressure is a reasonable indicator of overall heat exchanger functionality.

The dp setpoint from plant startup until January 1986 was 110 inches, which resulted in a standing alarm. From January 1986 until April 1988, the dp setpoint was 170 inches. From April 1988 until September 1989, the dp setpoint was 167 inches. From September 1989 until November 1989, the setpoint was 120 inches. The current setpoint of 140 inches was initiated in November 1989.

l Based on a review of the above macrofouling information, I it was determined that the limiting combination of macrofouling and high ocean temperature occurred on November 8, 1987.

d. Operational Controls As discussed above, PG&E enhanced its emergency procedures in February 1989 to place a second CCW heat exchanger.in service if both ASW pumps fail to start following an accident. The emergency procedures were further enhanced in 1991 to include directions regarding equipment configurations to control CCW temperature during recirculation.

6475S 1 i

)

l. .. .

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 220923

,aa a n - m x act - t. m u . -, t . ,., ..,,,,m vua u . o s.

DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 93 -

0l 1l 2 -

0l1 7 l 'l 16 TIAT (27)

4. Heat Exchanger Performance Testing On February 2, 1991, in response to the requirements of GL 89-13, PG&E performed testing of the Unit 1 CCW heat exchangers to verify their capability to meet design basis (nameplate) heat removal requirements.

The performance results were:

COMPONENT HEAT EXCHANGE RATIO CCW HX l-1 1.080 CCW HX l-2 0.987 ,

On September 1, 1991, PG&E performed testing of the Unit 2 CCW heat exchangers. The performance results were:

COMPONENT HEAT EXCHANGE RATIO CCW HX 2-1 1.112 CCW HX 2-2 1.109 Based on consultation with an industry heat exchanger expert and further evaluation of the test results, PG&E now concludes that the CCW 1-2 heat exchanger testing results (which were evaluated using Heat Transfer Consultants, Inc.'s HTC-STX computer model) did not meet the design basis. However, PG&E requested HOLTEC, International to analyze the GL 89-13 test data for the CCW 1-2 heat exchanger. The HOLTEC model was specifically developed for GL 89-13 evaluation and  ;

has been widely used by the nuclear power industry. It has been  ;

validated using an approved software quality assurance program and has been used in audit responses; therefore, it is considered a good validation of the HTC-STX program. The results of the HOLTEC model reanalysis of the GL 89-13 test data predicted that the CCW 1-2 heat 1 exchanger performance at nameplate condition would be 101 percent with l a 95 percent confidence level. l

)

Additional testing on the Unit 1 CCW heat exchanger was completed on  !

April 26, 1994. These tests indicate that the heat exchangers have )

significant margin above design basis and that both Unit I heat i exchangers are performing significantly better than the 1991 GL 89-13 test results described above. The results of the tests are as follows:

COMPONENT HEAT EXCHANGER RATIO CCW HX 1-1 1.176 CCW HX 1 1.160

5. Conclusion On December 30, 1993, at 1150 PST, with Unit 1 in Mode 3 (Hot Standby) at 0 percent power and Unit 2 in Mode 1 (Power Operation) at 64755 ,

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 22()g23  :

,mm n .- m xo u ~-n a m

, u.y. ,e _

.m . m DIABLO CANYON UNIT 1 Ol 5l 0l 0l 0l 2 l 7 l 5 93 -

0l1l2 -

0l1 8 l"I 16 Tut (n) 100 percent power, PG&E determined that the CCW heat exchangers for both units may have not met their design basis prior to implementation of continuous chlorination. This condition was reported to the NRC as a one-hour, non-emergency report in accordance with 10 CFR 50.72 (b)(1)(ii)(B) at 1150 PST on December 30, 1993. Continuous chlorination was fully implemented in September and November 1992 for Units 1 and 2, respectfully.

The continuing in','estigation reviewed the current maintenance, operational, and testing practices. The maintenance practices that provide assurance that the heat exchangers will remain sufficiently clean of biofouling include continuous chlorination, scraping of the tubes during refueling outages, cleaning of the tubes and tubesheet when the measured dp is 130 inches of water, and declaring the heat exchanger inoperable at 140 inches of water.

The review of historical information determined that a combination of three factors led to the microfouling growth discovered in CCW 1-2 heat exchanger in August 1990. Chlorination was not performed for a period of approximately six months prior to the Unit I heat exchanger inspections. During this period, the gaseous chlorine system was out of service for replacement of cast iron piping. Concurrent with the  !

absence of chlorine, the following unusual environmental conditions  ;

contributed to the microfouling:

)

• Beginning in March 1990 and continuing through June, coastal I upwelling was experienced. This upwelling increased the I nutrient level of the ocean surface waters.

• The high nutrient level, when combined with the rising ambient ,

ocean temperature in July and August, and the absence of I chlorine injection, produced ideal conditions for microfouling organisms such as bacteria, diatoms, and filamentous algae.

• CCW 1-2 heat exchanger was the only CCW heat exchanger that was ,

not waterjetted or scraped within seven months prior to '

conducting the performance test.

In summary, PG&E's review of the operating history of the CCW heat l exchangers from plant startup to date resulted in further review of the following periods for potential safety significance:

• Current ASW system condition (after full implementation of continuous chlorination in November 1992). .

• System condition between August 1990 and February 1991.

I 6475S

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION DOCKET N#8ta (2) 220923 eag FOCJLITY MAM( (3) ( t a n,we g o , o ,p

.. u .

og .,

DIABLO CANYON UNIT 1 0l 5l 0l 0l 0l 2 l 7l 5 93 -

0l1l2 -

Oil 9 lo'l 16 IEAT (17) e Operation between August 1986 and March 1988 (operation with a dp setpoint alarm of 170 inches).

D. Inoperable Structures, Components, or Systems that Contributed to the Event:

1 Chlorination was not performed for a six-month period of time in 1990

~

due to the replacement of cast iron piping in the chlorination and associated systems.

E. Dates and Approximate Times for Major Occurrences:

1. July 18, 1989: Generic Letter 89-13 was issued.

2. August 23, 1990: Samples taken from CCW 1-2 heat exchanger, indicating excessive microfouling.

3. February 1991: Unit 1 GL 89-13 heat exchanger testing.

4. September 1991: Unit 2 GL 89-13 heat exchanger testing.

5. November 1992: Continuous chlorination fully l implemented for ASW system.

6. July 28, 1993: QA surveillance report issued.

1

7. December 30, 1993: Event / Discovery date. PG&E l determined that CCW 1-2 heat I exchanger may have had sufficient microfouling to preclude the CCW system from meeting its design basis on August 23, 1990.

F. Other Systems or Secondary Functions Affected:

None.

G. Method of Discovery:

During a TRG evaluation of an engineering reanalysis, PG&E determined that CCW 1-2 heat exchanger may have had sufficient fouling to have i precluded the CCW system from meeting its design basis on August 23, 1990.

l 6475S

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 220923 AC3LIIT MAME (3) DOCrti NUH8(R (2) _,

({G acpa,( 9 (61 p a r,{ rp

". 20' OL' DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 93 -

OlII2 -

0l1 10 l 'l 16 EAT (17)

H. Operators Actions:

None required.

I. Safety System Responses:

None required.

III. Cause of the Event A. Immediate Cause:

Fouling.

B. Root Cause:

The root cause of this event is an inadequate understanding of the l effects of fouling on the CCW beat exchangers. l 1

C. Contributing Cause:

1. Chlorination frequency.

2. Mechanical cleaning frequency.

IV. Analysis of the Event ,

The key parameters affecting the performance of the ASW and CCW systems include: macrofouling and microfoultng, ASW flow, and ocean temperature.

An extensive review of historical maintrance, testing, operational, and biological factors was performed to identify time periods with a high potential for macrofouling and microfouling. During this review of past  ;

operation, specific periods of time have been identified during which one or more of these key parameters may have been outside current acceptance criteria. These time periods, and the safety significance of the associated  ;

fouling, are discussed below.

Biological Fouling Conditions The potential for significant microfouling of CCW heat exchanger tubes occurs when certain conditions are met. These conditions include: i

• An upwelling of cold, nutrient-rich water from deep ocean layers, which' occurs as a result of strong northwesterly winds that 4 characteristically blow during the spring.

• A period of high ocean temperatures, which, following an upwelling period, allows the microorganisms to " bloom." Experience indicates 64755

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 220923

,om - m =a u -.a m

, m = m,

~ , ,

DIABLO CANYON UtlIT 1 0l 5l 0l 0l 0l 2 l 7 l 5 93 -

0l1l2 -

0l1 11 lo'l 16 101 (17) that ocean temperatures of approximately 58 F or greater must be reached over a several week period for the " bloom" to occur.

• The chlorination system is out-of-service for a considerable period prior to and during the " bloom." Without chlorination during the

" bloom" period, microfouling could form on the tubes of the heat exchanger. If chlorination is restarted after the " bloom" has occurred, further microfouling is stopped. However, residual material placed by the microorganisms remains in the tubes as a coating and continues to irrpact heat exchanger performance. Once deposited, waterjetting or scraping of the tubes is needed to remove the residual material.

Bounding Microfouling Condition PG&E's evaluation of maintenance and operational pract;m eu biablo Canyon's operating history indicates that the bounding conditions for potentially significant microfouling only occurred during August 1990.

Prior to this period, upwelling of nutrients had occurred and was followed by a period of ocean warming. As a result, a microfouling " bloom" occurred.

PG&E's analysis indicates that microfouling reached significant levels in August 1990 as ocean temperature exceeded 58"F. In addition, the chlorination system was out-of-service during this period while PG&E was replacing cast iron piping in the system. When batch chlorination was restored on August 21, 1990, further microfouling ceased. However, the residual material from the microorganisms remained in the CCW heat exchanger tubes until waterjetting or tube scraping was performed. PG&E's review indicates that there were no other time periods when the lack of '

chlorination and maintenance was coupled with favorable environmental conditions for microfouling.

Of the four CCW heat exchangers, the 1-2 heat exchanger was the most susceptible to microfouling based on its chlorination, maintenance, and operating history. The remaining three heat exchangers received waterjet cleanings between the period of high microfouling potential and the performance of the GL 89-13 performance testing. In addition, two of the other three heat exchangers were operated less frequently during the period of high microfouling potential.

The CCW 1-2 heat exchanger was not waterjetted or scraped during the period from August 1990 until after the performance of the GL 89-13 performance test in February 1991. However, as discussed above, batch chlorination was resumed on August 21, 1990, and PG&E's reanalysis of the February 1991 CCW 1-2 heat exchanger performance test using a certified test model indicates that the CCW 1-2 heat exchanger met its design basis (nameplate) beat removal capacity at that time. PG&E believes that the heat transfer microfouling characteristics of the CCW 1-2 heat exchanger during its associated GL 89-13 testing represent the bounding microfouling case.

64755

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION g,gg

,mm. - m = u, -.a m u. - . .., . . , , .

vtaa u at a o i DIABLO CANYON UNIT 1 0l 5l 0l 0l 0l 2 l 7 l 5 93 -

0l 1l 2 -

0l1 12 l 'l 16 rui (27)

PG&E evaluated the highest macrofouling that may have existed coincident with high microfouling. During August 1990, the CCW 1-2 heat exchanger was taken out of service for cleaning. It was not again taken out of service until the test in February 1991, at which time the dp was about 110 inches.

The August 1990 dp of about 130 inches represented the highest macrofouling reached during this bounding microfouling period. The level of macrofouling associated with a dp of 130 inches, coupled with an assumed level of microfouling found during the testing of the CCW 1-2 heat exchanger, represents the most limiting fouling of a CCW heat exchanger.

Bounding Macrofouling Condition PG&E's review of macrofouling data identified periods of operation at an elevated dp (greater than 140 inches). The historical data focused attention on a period from August 1986 to March 1988 during which, on three occasions, the combination of recorded dp and actual ASW temperatures indicated the potential for excessive macrofouling. The apparent bounding case of macrofouling identified in this period occurred on November 8, 1987, when CCW 1-2 heat exchanger was removed from service with a dp of about 170 inches in conjunction with an ocean water daily mean temperature of 59.9 F. A review of environmental conditions associated with this period of high dp determined that coincident conditions required for significant microfouling did not exist. PG&E believes that microfouling levels at that time were consistent with the low levels observed during the Unit 2 CCW heat exchanger GL 89-13 tests.

Safety Significance j PG&E has analyzed the bounding cases of heat exchanger fouling for safety I significance. These analyses were performed using the mass and energy (M&E) ,

release model that is the licensing basis for DCPP. '

The impact of bounding fouling cases on the containment integrity analyses was performed by Westinghouse. Westinghouse evaluated the design basis LOCA, as well as the limiting MSLB accidents for impacts on containment pressure and temperature. The conclusion of these evaluations is that the containment design basis pressure and temperature would not have been exceeded during a postulated LOCA or MSLB.

i The design basis CCW temperature limits allow a transient temperature  ;

maximum of 132' F for 20 minutes. The temperature limit for continuous i I

operation is 120' F. PG&E has evaluated the impact of the bounding fouling cases on the limiting post-LOCA CCW temperature transients. Using the i current licensing basis M&E release model, PG&E and Westinghouse have l i

determined that the peak CCW temperature would have remained within the '

design basis CCW temperature limits during the injection phase following a LOCA. The containment conditions calculated by Westinghouse were then used by PG&E to evaluate the CCW temperature transient that would result during 64755

I LICENSEE EVENT REPORT (LER) TEXT CONTINUATION xa n -u . m a..~-- e, 220923

...-m . . s, o ,

vua sa m a o DIABLO CANYON UNIT 1 0l5l010l0l2l7l5 93 -

0l1l2 -

0l1 13 l6'I 16 701 (17) the recirculation phase. These evaluations concluded that the CCW temperature could have exceeded its design basis temperature limits in recirculation for an extended period if operator action is not taken.

The potential for the CCW system to overheat during the post-LOCA recirculation phase of an accident was previously identified by PG&E in 1991. LER 1-91-018, " Component Cooling Water System Outside Design Basis,"

reported that the heat load during cold leg recirculation may exceed the CCW system design basis temperature limits. Specific recirculation transient analyses were not performed. At that time, it was reported that operator action to keep CCW temperatures within design limits was required if the two ASW pump /two CCW heat exchanger configuration could not be established. In response to the LER, guidance to address conditions when both ASW pumps and both CCW heat exchangers were not available was incorporated into step 3.d of E0P E-1.3 in 1991. The potential for elevated CCW temperatures identified in the bounding fouling cases above is due primarily to the heat loads imposed on the system during recirculation, and not specifically caused by the identified heat exchanger fouling. Calculations indicate that, had the 1991 E0P guidance been in place at the time that the bounding conditions existed, the CCW system temperature would have remained within its design basis.

To bound the conditions in place during the 1990 high macro- and microfouling case, as well as the 1987 high macrofouling case, PG&E evaluated the CCW temperature transient assuming the likely operator actions for each period. Prior to the 1991 revision of E0P E-1.3, E0P E-0 was revised in 1989 to require placing a second CCW heat exchanger in service when only one ASW pump is available (post-LOCA). Because of the enhanced procedural guidance available to the operators in 1990, the timeline for the period of high microfouling had the operators align the second heat exchanger within 20 minutes following the initiation of the LOCA (This is consistent with operator action described in SSER 16.). A different timeline was used for the period of high macrofouling as this case preceded the 1989 E0P changes. While not formally proceduralized, operator actio s believed to be representative of those actions that would have occurred prior to the 1989 E0P changes were used. The timeline would have operators i secure two CFCUs 15 minutes after the start of recirculation in response to high CCW temperature alarms and subsequently place the second CCW heat exchanger into service 10 minutes later.

Assuming operator action as described above, the limiting CCW temperature transients were evaluated. The peak Cr" temperature for the high macro- and microfouling case was approximately : , and the cumulative time above l 120*F was approximately 30 minutes. Sak CCW temperature for the high I macrofouling period was appre " "F, and the cumulative time above 120*F was approximately 34 mu impact of the elevated CCW temperatures on the components of t u. al CCW headers was evaluated.

Westinghouse analyzed the impact of tr CW temperature profile and has 64755 ,

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION ggy FAs]L]TV HAM ( (j) CCCFET NVM8(2 (2) tra w pgge f6) pa g eji vtAn SE aAL a 24 DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 93 -

0l1l2 -

0l1 14 l 'l 16 f(af (27) determined that the SI and RHR pumps and the CFCU fan motors would perform their design basis function. The CCW pump manufacturer confirmed that the CCW pumps would perform their design basis function at the elevated CCW temperatures. The post-LOCA sampling system may have been temporarily-disabled by the elevated CCW temperatures. However, the ability to assess '

core damage remained available from alternate proceduralized means. The centrifugal charging pumps (CCPs) cannot be shown to continue to be available at these elevated temperatures, although the exact point of failure is not known. However, the CCPs are available for the entire injection phase of the accident. Regardless of the availability of the CCPs for the recirculation phase, Westinghouse and PG&E analyses have determined that during the recirculation phase, other ECCS pumps are available to perform required ECCS functions.

Based on the foregoing detailed analysis of this event, PG&E concludes the following:

e The fouling identified on the CCW heat exchangers would not have resulted in the containment design pressure or temperature being exceeded.

• The CCW design basis temperature limits would only have been exceeded during post-LOCA recirculation.

• All vital components served by the CCW system would have continued to  :

perform their design basis function, or redundant equipment would have  ;

been available to perform these functions. ,

Accordingly, this event had no safety significance and the health and safety of the public would not have been affected.

V. Corrective Actions A. Immediate Corrective Actions: [

1. An operations standing order was prepared to notify the system engineer if the ASW chlorination system becomes  ;

. inoperable. This will provide assurance that the '

chlorination system is returned to service quickly enough to i prevent excessive CCW heat exchanger microfouling. ,

r

2. An operations standing order was prepared to ensure that the CCW heat exchangers are cleaned when the dp reaches 130 inches. In addition,'the associated ASW train will be declared inoperable whenever the dp reaches 140 inches.

This standing order is applicable for an operating j configuration of one ASW pump running with one CCW HX i aligned.  :

64755

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION ,,

g

,m m, - m --m u. g . ,,, .m o ,

DIABLO CANYON UNIT 1 0l 5l 0l 0l 0l 2 l 7 l 5 93 -

0l1l2 -

0l1 15 l 'l 16 TfAT (17)

3. STP I-1A, " Routine Shift Checks Required by Licenses," has been revised to require that the CCW heat exchanger dp be verified to be less than 140 incnes of water. This revision will incorporate the existing standing order to begin preparations to clean the heat exchangers at 130 inches.

B. Corrective Actions to Prevent Recurrence:

1. The continuous chlorination program for the ASW system has been fully implemented. ASW system continuous chlorination effectively controls the effects of biofouling.

2. In addition to inspections performed when dp limits are reached, a recurring task work order will be initiated to assure that each heat exchanger will be inspected at a frequency of six months and cleaned as required.

3. Additional CCW heat exchanger performance tests on both units will be performed to verify the adequacy of operational and maintenance practices to assure that the CCW heat exchangers meet design basis requirements. The tests will be conducted during the IR6 and 2R6 refueling outages and will include dp measurement. Upon completion of additional heat exchanger performance tests scheduled for 1R6 and 2R6, PG&E will reevaluate the dp setpoint.

4. Enhanced ASW flow instrumentation will be installed with local readouts.

5. ECG 17.2 has been approved to provide administrative controls on the ASW chlorination system. This ECG will document compensating actions to be taken if the ASW chlorination system is inoperable for greater than 14 days.

6. PG&E agrees that trending of the dp increase on each CCW heat exchanger would be useful in anticipating calcification and other buildup that may affect dp. Consequently, PG&E will revise STP M-26 to require a formal trending program to monitor this parameter.

7. An Integrated Problem Response Team (IPRT) will be conducted on the ASW, CCW, and interfacing systems by the end of 1994.

This IPRT will thoroughly and critically review these systems. Membership of the IPRT will include operations, quality services, maintenance, Westinghouse, and engineering personnel. Based on the results of the IPRT, DCM S-17B will 64755

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 220923 FACILJTV NAs.( (1) DOCEEI NUMBER (2) tfD NUMBER f6) pagg #3i vtAsl SE int hives 08:

DIABLO CANYON UNIT 1 0l5l0l0l0l2l7l5 93 -

0l1l2 -

0l1 16 l 'l 16 TEAf (37) be revised to provide additional information on ASW system heat removal capacity.

VI. Additional Information A. Failed Components:

None.

B. Previous LERs on Similar Problems: ,

2

1. LER l-91-018-01, " Component Cooling Water System Outside Design Basis Due to Personnel Error."  ;

PG&E determined that the heat load on the CCW system during I the cold-leg recirculation phase following a LOCA could potentially exceed the CCW system design basis temperature limits. Because the injection phase had previously been ,

I considered the limiting case for CCW temperature, this condition was considered to be outside the design basis of j the CCW system. The root cause was attributed to personnel l error. The corrective actions to prevent recurrence I included additional training for design engineers to l emphasize that data known to be conservative for one j application may be nonconservative for another application.

Because this event did not address the potential for biofouling of heat exchangers, the corrective actions taken would not have prevented the current event.

2. LER 1-84-040, "CCW and ASW System Design Basis Requirements Not Incorporated into Plant Procedures Due to Inadequate Tracking of Resolution from Correspondence and Communication."  !

Engineering recommendations for plant operation to assure compliance with the design basis for the CCW and ASW systems were not incorporated in plant procedures. Since this event involved incorporation of design constraints in plant ,

procedures, corrective actions taken to prevent recurrence I could not have prevented the current event since they would not affect biofouling in the CCW heat exchangers.

64755

4 4 l

ATTACHMENT 6

'/  % UNITED STATES

., t NUCLEAR REGULATORY COMMISSION

( e ll g ,=*

l Walnut Creek Field Office RECEIVED

'% .,,,,, <

• 1450 Mana Lane sob 1 $ jgg4 Walnut Creek, Cahfornia 94596-5368 CHRISTOPHER J. WARNER l

AllG 1 0 1994 Dockets: 50-275 1 50-323 Licenses: DPR-80 DPR-82

)

Pacific Gas and Electric Company Nuclear Power Generation, B14A ATTN: Gregory M. Rueger, Senior Vice l President and General Manager l Nuclear Power Generation Bus. Unit l 77 Beale Street, Room 1451 P.O. Box 770000 San Francisco, California 94177

SUBJECT:

NRC INSPECTION REPORT l

l Thank you for your letter of August 5, 1994, in response to our letter and Notice of Violation dated July 14, 1994. We have reviewed your reply and find it responsive to the concerns raised in our Notice of Violation. We will )

l review the implementation of your corrective actions during a future

)

inspection to determine that full compliance has been achieved and will be I

! maintained.

1 Sincerely, 1

i

(

Kenneth E. erkins, Jr. i

} Director l

cc:

Sierra Club California ATTN: Dr. Richard Ferguson Energy Chair 6715 Rocky Canyon Creston, California 93432 l

1 Pacific Gas and Electic Company EG l 0 g l

San Luis'Obispo Mothers for Peace ATTN: Ms. Nancy Culver P.O. Box 164 Pismo Beach, California 93448 Ms. Jacquelyn C. Wheeler P.O. Box 164 Pismo Beach, California 93448 The County Telegram Tribune ATTN: Managing Editor 1321 Johnson Avenue P.O. Box 112 San Luis Obispo, California 93406 San Luis Obispo County Board of Supervisors ATTN: Chairman Room 370 ,

County Government Center San Luis Obispo, California 93408 California Public Utilities Commission ATTN: Mr. Truman Burns \Mr. Robert Kinosian 505 Van Ness, Rs. 4102 San Francisco, California 94102 Diablo Canyon Independent Safety Committee Attn: Robert R. Wellington, Esq.

Legal Counsel 857 Cass Street, Suite D Monterey, California 93940 Radiologic Health Branch State Department of Health Services ATTN: Mr. Steve Hsu P.O. Box 942732 Sacramento, California 94234 State of California ATTN: Mr. Peter H. Kaufman Deputy Attorney General 110 West A Street, Suite 700 San Diego, California 92101

Pacific Gas and Electic Company MG I 0 g Pacific Gas and Electric Company A1TN: Christopher J. Warner, Esq.

P.O. Box 7442 San Francisco, California 94120 Diablo Canyon Nuclear Power Plant ATTH: John Townsend, Vice President and Plant Manager P.O. Box 56 Avila Beach, California 93424 6

7 I

a e ATTACHMENT 7 i

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{\ -! NUCLEAR REGULATORY COMMISSION wasHiNoroN. o c. 2oses oooi 5 . .% 3.../ June 21. 1994

., RECEn/m Docket Nos. 50-275, 50-323

% '94 AUG -3 P1 :55 Mr. Richard A. Clarke Chairman of the Board PUBLIC DOCUMEh; -

and Chief Executive Officer Pacific Gas and Electric Company 77 Beale Street San Francisco, CA 94106

Dear Mr. Clarke:

On June 7-8, 1994, performance licensees. of operating reactors, fuel facilities, and oth The NRC conducts this meeting semiannually to determine if the .

warrant increased NRC attention or if it is trendin that steps board be taken to communicate concerns to the utility's president or of directors.

specific deserves plants formal that have demonstrated a level of NRC recognition. safety pe At the January 1994 Senior Management Meeting, achieved a the highDirblo level ofCanyon safety Nuclear Power Plant was identified as hav recognition of its performance. performance and, as a result, met criteria for again been identified as a good performer.I am pleased to note that Diablo Canyon h In identifying such plants, NRC senior managers perform an evaluation of problem resolution, and plant management organiza The NRC recognizes that, to achieve the level of performance demons the DiabloofCanyon all phases Nuclear Power Plant, there must be management invo plant activities.

In addition, the staff must be dedicated, knowledgeable, and fully supportive safety must exist throughout the organization.

of plant activities, and a commitment to for achieving this high level of safety performance.We commend you and your staff positive example to the industry. Your achievement is a The greatest challenge that you now face is to maintain this level of performance and not to rest on past achievements.

Continued management involvement and support, and dedicated efforts from your staff to identify an l

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9407210172 940621 PDR ADOCK 05000275 e- a p PDR 3g__

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u Mr. Richard A. Clarke -

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difficult correc problems are necessary for you to continue to meet this Originalsigned by James M.Taylw James M. Taylor Executive Director for Operations cc: See next page DISTRIBUTION:

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