ML20249A786

Informs That Licensee Closed Discrepancy Repts DR-MP3-0272, 0514 & 0580 & Providing NRC Info on Issues for Review

ML20249A786
Person / Time
Site:	Millstone
Issue date:	06/16/1998
From:	Schopfer D SARGENT & LUNDY, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
9583-100, NUDOCS 9806180237
Download: ML20249A786 (28)

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Don K. Schopfer l Senior Vee President l 312 269 6078 l

l June 16,1998 Project No. 9583-100 Docket No. 50-423 Northeast Nuclear Energy Company Millstone Nuclear Power Station, Unit No. 3 Independent Corrective Action Verification Program United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Discrepancy repons (DR) DR-MP3-0272,0514, and 0580 documented discrepancies identified during the ICAVP review of design criteria documents and licensing basis documents for Millstone Unit 3 (M3). The issues raised in these DR's are related to the adequacy of the licensing basis rather than Northeast Utilities' (NU) compliance with the licensing basis. Afler discussing thh with Messrs. Travers and Imbro of the Nuclear Regulatory Commission (NRC), Sargent & Lundy, LLC (S&L) agreed that since these issues were not related to NU compliance with their licensing basis, the appropriate action I would be to close these DR's and to refer the issues to the NRC for resolution.

Accordingly, S&L has closed the DR's and is providing the NRC the information on these issues for their review; a copy of each DR is enclosed:

• DIt-M P3-0272 - Use of ASME Code Case N-411 for Millstone 3

/W)/

e DR-M P3-0514 - Single Point Differential Pressure Measurement

• DR-MP3-0580 - Secondary Containment Drawdown Test 9806180237 900616 '

PDR ADOCK 05000423 P PDR 55 East Monroe Street Chicago, IL 60003-5780 USA

• 312 269-2000

-a ~ t June 16,1998 I

. United States Nuclear Regulatory Commission Document Control Desk Project No. 9583-100 Page 2 4 l

Please direct any questions to me at (312) 269-6078.

Yours very truly, 1.7 ~~

D.K.S pfer -

Sr. Vice President and ICAVP Manager DKS:spr Enclosures Copies:

E. Imbro (1/l) Deputy Director, ICAVP Oversight T. Concannon (1/l) Nuclear Energy Advisory Council J. Fougere (1/1) NU

.nsenyouws w ,va w 1

t V Northsatt Utilitias ICAVP DR No. DR-MP3-0272 Millstone Unit 3 Discrepancy Report Review Group: system DR RESOLUTION ACCEPTED Review Element: system Design Discipline: Piping Desgn Potential Operability issue Discrepancy Type: Calculaton Om l system / Process: N/A gg NRC Significance level: NA Date faxed to NO:

Date Published: 10/10/97 Discrepancy: Discrepancy associated with the implementation of Code Case N-411

Description:

In the process of reviewing the following documents, (i) FSAR Section 3.78.3.1.2 Seismic Analysis Methods - Piping Systems (ii) Pipe Stress Analysis Criteria Document, NETM-44, Revision 2

(iii) NRC Regulatory Guide 1.84: Design and Fabrication Code Case Acceptability - ASME Section ll1 Division 1 (iv) NUREG/CR-3526 Impact of Changes in Damping and Spectrum Peak Broadening on the Seismic Response of Piping Systems (v) NRC Regulatory Guide 1.60: Design Response Spectra for Seismic Design of Nuclear Power Plants (vi) NRC Regulatory Guide 1.61: Damping Values for Seismic Design of Nuclear Power Plants (vii) NRC Regulatory Guide 1.92: Combining Modal Response and Spatial Components in Seismic Response Analysis, Rev.1 (viii) NRC Regulatory Guide 1.122: Development of Floor Design Response Spectra for Seismic Design of Floor-Supported Equipment or Components, Rev.1 (ix) FSAR Table - 1.8.1 NRC Regulatory Guides (x) NU Letters: Dated October, 10,1984 and November 9,1984 (xi) NRC Letter: Dated November 16,1984 According to (i): Damping values used for piping are 0.5 percent for OBE and 1 percent for SSE except that increased damping values may be applied on an as-needed basis for final stress reconciliation in accordance with ASME Code Case N-411.

According to (ii): ASME lil Code Case N-411 is to be used on a limited basis for stress reconciliation as specified by the lead engineer. Also when these attemate damping values are used for developing pipe support loads, additionalload cases must be specified to account for any applicable secondary type loads occurring during the plant faulted condition. All affected pipe supports shall be evaluated with these additional specified loads but the pipe stress criteria will remain unchanged. Where attemate damping values are used exclusively for evaluating equipment loading, valve acceleration or local IWA stress, the additionalload cases mentioned above need not be considered by supports or stress.

According to (iii): Code Case N-411 is acceptable subject to the following conditions in addition to those conditions specified in the Code Case: (1) The Code Case damping should be used mmnlatolv nnd mncittantly' if uwd nt nfl I'A The damninn Pnnted 6/1998 4:32:32 PM ' Piige 1 of 5

g N:rthe=t Utilities ICAVP DR N3. DR-MP3-0272 Millstone Unit 3 Discrepancy Report values specified may be used only in those analyses in which current seismic spectra and procedures have been employed.

Such use should be limited only to response spectra analyses (similar to that used in the study supporting its acceptance -

Reference NUREG/CR-3526).

The study supporting the code case accepta. ice (iv) addresses sources of conservatism in the seismic analysis procedure whl:h is based on a consistent utilization of the methodology delineated in NRC Regulatory Guides 1.60,1.61,1.92 and 1.122

[(v) to (viii)). The objective of the study was to determine the impact of proposed changes to RG 1.61 damping values (Code Case N-411) and the spectrum peak broadening procedure of RG 1.122 on the level of conservatism remaining in the analysis.

Conservatism is introduced in the analysis process in numerous ways, among them, due to the broad-band seismic input (RG 1.60) and modal combination methods (RG 1.92).

According to (ix): Millstone-3 is not required to, and does not, consistently comply with Regulatory Guides 1.60,1.61,1.92 and 1.122.

As identified in (x) and (xi): Millstone-3 requested and was granted NRC approval for the use of Code Case N-411. This approval forms the basis for its application in (i) and (ii).

Discrepancy:

The ' additional load cases' that *must be specified to account for any applicable secondary type loads' as referred to in (ii), have not been defined. Also, it is not clear whether the ' additional load cases' have to be considered for evaluating equipment loading, valve acceleration and/or IWA stress.

Code case N-411 is implemented in large bore pipe stress analysis calculations in certain cases exclusively foi evaluating equipment loading, valve acceleration or loca' iWA stress, and in others to reduce seismic stresses in the pipe. The code case is also implemented in small bore pipe stres9 analysis calculations to evaluate piping and supports. No ' additional load cases' have been specified in these calculations.

The use of Code Case N-411 is justified for reducing levels of conservatism inherent in pipe stress analyses which are based on consistent use of the methodology defineated in Regulatory Guides 1.60,1.61,1.92 and 1.122. The seismic design basis for Millstone-3 is not required to, and does not, comply with these Regulatory Guides. Therefore, the Millstone Piping Design Criteria (ii) does not fulfill the conditions set forth in Regulatory Guide 1.84.

Review Valid invalid Needed Date Inidator: Prakash, A-0 0 0 S'1S/S7 VT Lead: Neri, Anthony A O O O 9/23 87 VT Mar: schoofer. Don K 9/30/97 Pnnted 6/19/96 4:32:33 PM Page 2 of 5 L - - - _ - -

4 I

• Northeast Utilities ICAVP DR No. DR-MP3-0272 l Millstone Unit 3 Discrepancy Report l VT Mgr: schopfer, Don K B O O S'3o/87 1RC Chmn: singh, Anand K B O O ior2.S7 Date:

INVAllD:

Date: 5/21/98 RESOLUTION: Response ID: M3-IRF-02193 Disposition:

NU has concluded that the issue reported in Discrepancy Report, ,

DR-MP3-0272, does not represent a discrepant condition. With  !

respect to items 1 and 2, when invoking the use of ASME Code l Case N-411 there are no additional load cases required for the  !

evaluation of piping stresses, since all applicable load cases l which account for secondary effects have already been included in the pipe stress analysis. Additionalload cases are used to ensure that the secondary effects are considered in support j design. These additionalload cases are included in the Pipe l Support Design Criteria Document NETM-45, Revision 1, Change 5. Similar methods are employed for piping reactions to equipment.With regard to item 3, the use of ASME Code Case N-  ;

411 for Millstone 3 was only implemented after specific approval l was obtained from the NRC. By letter (attached) dated November 9,1984 Northeast Utilities requested NRC approval  ;

for the use of ASME Code Case N-411. This request indicated i the use of the Amplified Response Spectra Broadening procedure of Regulatory Guide 1.122 would be used with the Code Case Damping, but that all other FSAR commitments related to the Amplified Response Spectra would remain unchanged. The NRC approval for the use of ASME Code Case N-411 was gramed in a letter (attached) dated November 16, 1984 without further restriction on the Amplified Response Spectra techniques. It should also be noted that Regulatory Guide 1.84 does not require specific conformance to all of the mentioned Regulatory Guides. Since NRC approval was granted without any stipulation, Millstone 3 is in conformance with Regulatory Guide 1.84 with respect to the use of ASME Code Case N-411.

Significance Level criteria do not apply here as this is not a discrepant condition.

Conclusion:

NU has concluded that the issue reported in Discrepancy Report, DR-MP3-0272, does not represent a discrepant condition. For item 1 and 2, when invoking the use of ASME Code Case N-411 there are no additional load cases required since all applicable load cases which account for secondary effects have been included in the pipe stress analysis. Additional load cases are used to ensure that the secondary effects are considered in support design. For item 3, the use of ASME Code Case N-411 for Millstone 3 was only implemented after specific NRC approval. Northeast Utilities to NRC letter (attached) dated l Novernher 9 108L renuec;teri annrnval for the use of ASME Printed 6/19/98 4:32:33 PM Page 3 of 5 l

)

W N:rthe st Utilities ICAVP DR No. DR-MP3-0272 Millstone Unit 3 Discrepancy Report Code Case N-411. This request indicated the use of the Amplified Response Spectra Broadening procedure of Regulatory Guide 1.122 would be used with the Code Case l Damping, but that all other FSAR commitments related to the Amplified Response Spectra would remain unchanged. The NRC approval for the use of ASME Code Case N-411 was granted in a letter (attached) dated November 16,1984 without further restriction on the Amplified Response Spectra techniques. It should also be noted that Regulatory Guide 1.84 does not require specific conformance to all of the mentioned Regulatory Guides. Since NRC approval was granted without l any stipulation, Millstone 3 is in conformance with Regulatory Guide 1.84 with respect to the use of ASME Code Case N-411.

Significance Level criteria do not apply here as this is not a discrepant condition. I Attachments: l NU to NRC Letter dated November 9,1984 NRC to NU Letter dated November 16,1984 Previously identified by NU? O Yes @ No Non Discrepant Condition?(#) Yes O No Resolution Pending?O yes @ No Resolution Unresolved?O ves @ No Review init;ator: Prakash, A.

VT Lead: Neri, Anthony A VT Mgr: 3chopfer, Don K IRC Chrnn: singh, Anand K Date: 5/21/98 SL Cornments: We concur with NU that NRC approval to use ASME Code Case N-411 was granted without any stipulation. Therefore, we concur with NU that the subject issue does not represent a discrepant condition.

However, as noted below, we do not concur with NU's position regarding conformance with Reg Guide (RG) 1.84. This issue will be forwarded to the NRC.

As previously noted in the DR, acceptance of higher, less conservative, N411 damping values is justified on the basis of a study which eliminates conservatism in seismic analysis procedures that are based on consistent utilization of RG's 1.60, 1.61,1.92 and 1.122. Specifically, conservatism due to RG 1.61 is eliminated by replacing RG damping with higher N411 damping, while maintaining the conservatism introduced via remaining RG's.

In Ref. (i), SWEC addressed the issue, namely, *RG 1.61 damping values are to be used in conjunction with RG 1.60 which invokes the use of a new method for generating response spectra. The use of RG 1.61 damping values not in conjunction with the new (RG 1.60) spectra is questionable and ualicensable."

Pnnted 6/19/98 4:32:34 PM Page 4 of s I

i N:rthe ct Utilities ICAVP DR N2. DR-MP3-0272 Millstone Unit 3 Discrepancy Report If the use of RG 1.61 damping without RG 1.60 spectra is questionable, then it follows that the use of N411 damping, a less conservative replacement for RG 1.61, without RG 1.60 spectra is also questionable.

Another related issue with the implementation of N411 is inclusion of " residual mass" response in the modal combination.

This refers to the contribution of high-frequency modes which are beyond the frequency at which the spectral acceleration retums to the zero-period acceleration (ZPA). With the use of N411 damping, only the flexible range (low frequency) response is reduced, while the rigid range (high frequency) response to the ZPA remains unchanged. Therefore, the SRP 3.7.2 criteria -

" inclusion of additional modes does not result in more than a 10%

increase in response"- may require that further consideration be given to high frequency modes. Ref. (ii)

To ensure that high frequency modes are adequately and consistently addressed, the NRC has in many instances required l that, if N411 damping is used, the effect of " residual mass" response must be included in the modal cornbinations. The effect of " residual mass" response has not been addressed in any of the reviewed pipe stress analysis calculations, and no justification is provided in the calculations or the design criteria document as to why it can be ignored.

l l

References:

(i) Calculation NP(T)-001-X, Rev 0, Attachment I, Page A5, interoffice Memorandum," Damping Values for Seismic Design Millstone 3", dated 1/22/74.

(ii) NUREG-0800, Standard Review Plan, Section 3.7.2, Seismic System Analysis.

Pnnted 6/19/98 4.32.34 PM Page 5 of s C____-----___-_------ - - - - - . - - - - - - - - - - -

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rthest Utilities ICAVP DR No. DR-MP3-0514 Millstone Unit 3 Discrepancy Report Review Group: System DR RESOLUTION ACCEPTED Review Element: system Design p

Discipline: Mechanical Design Discrepancy Type: Test Requirements g

System / Process: HVX NRc Significance level: 4 Date faxed to NU:

Date Published: 11/13/97 Discrepancy: Containment Enclosure Building Negative Pressure

Description:

During review of the Supplementary Leak Collection and Release System (SLCRS) a discrepancy in the negative pressure required to be maintained in the Auxiliary Building at elevation 24'-6" was identified.

SER Section 6.2.3 states that the capacity of the SLCRS is sufficient to reduce and maintain a pressure of -0.25 in. water gauge throughout the enclosure building and contiguous buildings within 1 min after the accident, assuming wind velocity of 22 mph.

FSAR Section 6.2.3.3 states that the negative pressure is measured at Auxiliary Building 24-6 elevation and maintained per Technical Specifications at greater than or equal to 0.4 inches water gauge after a design accident (DBA). The 0.4 inch water gauge (iwg) negative pressure is measured at the Auxiliary Building 24-6 elevation in order to ensure a negative pressure in all areas inside the secondary containment boundary under most onsite meteorological conditions. 4 Drawing EM-2E-12 shows the high point of the containment structure enclosure as elevation 186'-2 3/4".

Calculation 92-071-339M3 Rev. O and change number 001 determine correction factors to account for the difference in pressure at the test location, elevation 112'-0" (top of SLCRS suction ductwork) and elevation 186*-2 3/4" (top of enclosure building) caused by differences in air temperature inside and outside the containment enclosure building. The 0.4 iwg negative differential pressure in FSAR Section 6.2.3.3 is the differential pressure at elevation 24'-6" needed inorder to maintain a 0.25 N/ g negative differential pressure at elevation 112'-0" with 0*F outside air temperature and 50'F containment enclosure building temperature. To maintain a 0.25 iwg negative differential pressure at the top of the containment enclosure building at these temperatures a 0.51 iwg negative differential pressure is needed at elevation 24'-6".

The calculation also contains a table that provides the required negative differential pressure at elevation 24'-6" for various indoor and outdoor air temperatures. For cases with the indoor air temperature' lower than the outdoor air temperature, the required test differential pressure at elevation 24'-6" is less than -

0.26 iwg which does not meet the requirement that all areas are maintained at a -0.25 iwg differential pressure.

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i Northeast Utilities ICAVP DR Ns. DR-MP3-0514 Millstone Unit 3 Discrepancy Report pressure distribution around the containment enclosure building.

Review Valid invalid Needed Date initiator: Stout, M. D. O O O 10/17/97 VT Lead: Neri, Anthony A y Q ] 11/1 A7 VT Mg.: schopfer, Don K 9 0 0 1 /6/97 l IRC Chmn: singh, Anand K 8 0 0 11/7/97 Date:

INV71.lD:

Date: 5/29/98 RESOLUTION: First Response NU has conc d that the issue reported in Discrepancy Report, DR-MP3-0514, does not represeni 3 discrepant condition.

Proposed Technical Specification Change Request 3-30-93 contains a letter to the NRC dated 11/4/93 which recommends the changes to the Tech Specs and states in part on page B 3/4 6-7 paragraph Si4.6.6.1 .

1 "In order to ensure a negative pressure in all areas inside the secondary containment bourdaiy under most meteorological conditions, the negative pressure acceptance criteria at the measured location is 0.4 iwg. It is recognized that there will be l an occasiorat meteorological condition under which slightly l positive pressure may exist at some localized portions of the boundary.. "

On 12/B/93 the NRC issued Amendment 87 along with its Safety Evaluation approving the changes to the Tech Specs. This would supersede any prior statements found in SER section 6.2.3.

Furthermore, there are no piping and electrical penetrations above elevation 69'-9" in the containment liner (Reference CTMT pipe penetration drawing 12179-EP-121 A-10 and EP-121B-8.) Therefore, if a leak did occur, it would be below the SLCRS duct suction.

CCN 001 to Calculation 92-071-339 M3 provided the in.i.; pendent calculation to establish the minimum negative pressure required by the SLCRS test at elevation 24'-6" u render minimum negative pressure of 0.25 iwg at elevation 112'-0"(iop of SLCRS suction duct, reference drawing EB-15M.) This is the basis that the NF<C accepted. The Tables in the calculation on pages 10 and il are based on the 186'-2 3/4" elevation.

Significance level criteria do not apply as this is not a discrepant condition.

l Second Responsa ',M3-IRF-1954)

NU has concluded that Discrepancy Report DR-MP3-0514, item id, has idantified a condific,n not previously discovered by NU Pnnted 6/1W98 4.33:04 PM Page 2 of 8 i

Northeast Utilities ICAVP DR N1 DR-MP3-0514 Millstone Unit 3 Discrepancy Report which requires correction.

(id) Fire Stops and Seals are govemed by the EM-60 series drawings in conjunction with specification SP-GD-001. The flex.

seat referred to is an architectural cosmetic feature. The

• Rodofoam" (compress!ble material) was ali removed, but the drawings referenced were not updated. The approved corrective action to CR-M3-98-0772 will revise the affected drawings. The affected documents are not operations aitical.

(1) (General) Bypass Jumper 3-93-170 provided for the installation of two tubing penetrations to measure differential pessure , . cross 'he Contai.iment Enclosure. The Bypass Jumper was made a permanent modification. DCN DM3-S-1254-95 (copy attached) details location and installation of the pertranent pressure taps.

(1a) The Hydrogen Recombiner Bldg is not within the SLCRS boundary. Its common wall with the Containment Enclosure acts as a boundary for SLCRS. Differentiti pressure was measured in the MSVB which is drawn down via the Enclosure Bldg. ,

therefore the MSVB differential pressure readings provide  :

conservative indication of the Enclosure Bldg. differential l pressure. This is not a discrepancy. l (1b) Same as above.

(ic) The measurement location was selected to elimir, ate the )

effect of wind veiccity on the actual DP measurement. During testing, the door to the extemal t;nvironment was opened to ensure the high side tap was reflective of external pressure.

This is considered to be a more reliable appraach to measuring the DP as it elim: nates any dynamic effect by wind pattems at the measurement location. Ref. dravring no. 25212-2d.QS-00001 (12179-EB-358) Ventilation and Air conditioning Service Building Sh. 2. This is not a discrepancy.

(2) The drawings referenced correctly show that the duct is blanked off and the sample room dampers normally closed.

Although the statement that the blanked off duct is not consistent with the statement in the 11/4/93 submittal, the degree to which the NRC relied on this information is judged to be low. The SER for Amendment 87 makes no reference to the paragraph on page 14 of the 11/4/93 submittal, but pieces emphasis on the NRC review of the test data used by NNECo to justify the measurement location. The SER also acknowledges that on!y parts of the contiguous spaces listed are included in the SLCRS boundary (ref. page 5, use of term " partially"). This implies that at some level in the supporting discussion surrounding the

iEsuance of this amendment that the extent to which the spaces were included in the SLCRS boundary area was discussed and

(

clarified. While the discussion in the text of page 14 is inaccurate to some degree, it is judged to have been insignificant or immaterial to the NRC approval of the amendment. The normally closed sample room dampers are acceptable because this room is outside the SLCRS boundary.

Prned 6/191984 33 04 PM Page 3 of 8 L____________________.__________________

. Northemt Utilitica ICAVP DR No. DR-MP3-0514 Ministone Unit 3 Discrepancy Report This is not a discrepancy.

(3) This concern was addressed 5 the 11/4/93 submittal in that an analysis was performed to deteanine the joint probability of occurrence of wind and temperature conditions which could cause a reduction in the required building DP. NNECo addressed this as a low probability condition in paragraph 3 on page 15 of the 11/4/93 submittal. The NRC reviewed NNECc's basis and accepted it in the Amendment 87 SER. This is not a discrepancy.

(4) The NNECo evaluation of IEN-88-76 was based on the joint probability of occurrence of the atmospheric conditions rather than the discreet frequencies. The NRC reviewed the NNECo logic and accepted it explicitly in the SER. The approved corrective action to CR-M3-98-0772 will retrieve this analysis for confirmatory review. Justification for the "<2% time"is detailed in Calculation XX-XXX-115RA, Rev. O. A copy is attached for your information. This is not a discrepancy.

(5.1 & 5.2) The -0.51 iwg DP value cited would be required if the design were based on achieving a minimum of-0.25 iwg DP under all conditions. As noted in the 11/4/93 submittal, the proposed acceptance value of -0.4 iwg was not intended to taound all conditions.

(5.3) The extreme environmental conditions described in IEN ,

88 76 were addressed through the joint probability evaluation previously discussed and excluded on the basis that they occurred <2% of the time. (See attached calculation XX-XXX-115RA, Rev. 0) This is not a discrepancy.

The test rig locations listed on the Test Rig Location Diagram in IST 3-93-045 are explained on the attachment titled Test Rig Locations IST 3-93-04G. (This is in response to S&L's request per NU/S&L telecon 3/25/98).

Licenshg basis / design basis not affected by the discrepant conditions. NU considers the discrepant item 1d to be Significance Level 4. The corrective action will be completed post startup.

Attachments:

CR-M3-98-0772 with approved corrective action plan Calculation XX-XXX-115RA, Rev. O DCN DM3-S-1254-95 Test Rig Locations IST 3-93-045 Supplemental Response (M3-lRF-2322) l -

This response supplements M3-IRF-01954. At a meeting held

on 4/14/98 at Millstone, S&L requested additionalinformation concerning the SLCRS Verification Test.

A copy of MP3 Surveillance Procedure SP 36141.3, Rev. 9, is

! attached to this transmission. Step 4.1.5.b is an instruction to Pnnted 6/19/98 4:33 04 PM Page 4 of e

" Northeast Utilities ICAVP DR No. DR-MP3-0514 Millstone Unit 3 Discrepancy Report 3

block open "at least one side of the Service Building east corridor north docr (S-24-20)".

To supplement information provided in M3-lRF 01954, a copy of MP3 Surveillance Procedure SP 36141.3, Rev. 9, is attached to this transmission. Alto, IST 3-93-046 was the last test performed irl which multipl's measuring points were used. The difference between the MSVB and the AB (PDIT212) readings (0.05) is insignificant. Both areas met the required negative pressure at 40 seconds and both areas were significantly more negative than 0.40" WG at 120 seconds.

Attachments:

SP 36141.3 Supplementary Leak Collection and Release System Negrtive Pressure Verification Previously identifMHf by NU? O yes (9) No Nose Discrepant Condition?Q ves (4) No Resolution P6nding?O ve. @ No Resoiution unresoived?O yes @ No Review initiator: stout, M. D.

VT Lead: Neri, Anthony A VT Mgr: schopfer, Don K IRC Chmn: Singh, Anar'd K oste: 5/29/98 st. comments: Comments on First Response NU's response does not fully a ress the issues identified in the discrepancy report.

1) NU Letter B14669 dated November 4,1993, which transmitted the proposed technical specification change request for the supplementary leak collection and release system, provides a discussion for using a single point pressure measurement location. The argument was that there is a large open area between the various buildings and provides a table of the area of the openings. Looking at the areas provicted in the letter it would seem that a single measurement location is reasonable.

However, when the physical details for the 4" shake space between the containment structure and the surrounding buildings, IST 3-93-045 test results, and IST 3-93-046 test results are reviewed it is not obvious that a single point pressure measurement at elevation 24*-6"is representative of the presstare for the whole structure.

a) IST 3-93-045 conducted on 10/24/943 measured differential pressures in the auxiliary building, ESF Building, and main steam valve building (per Attachment 1 Test Rig Locations). Differential pressures where not measured in the hydrogen recombiner building and the containment enclosure during the drawdown test.

b) IST 3-93-046 conducted on 10/27/93 measured differential pressures in the auxiliary building, ESF building, and main steam valve building (per Attachment 1 Test Rig Locations). Differential pressures where not measured in the hydrogen recombiner Pnnted 6/19/98 433.04 PM Par,e 5 of 8 l

l L_ _ _ _ _ _ _ _ _ . _ _ _ _

l l

l s N rthea:t Utilities ICAVP DR No. DR-MP3-0514 Millstone Unit 3 Discrepancy Report building and cont 6inment enclosure during the drawdown test. I c) The auxilary building elevation 24'-6" general area measurement records the differential pressure between the auxiliary building and the service building. Depending on the relative pressure of the service building to the outside, the actual auxiliary building differential pressure with respect to outside could be different than that read on 3HVR-PDIT212.

d) Drawing EA-1S-1 section 5-5 shows a flex sealin the shake space between the ESF building and Containment Stucture.

Drawing EA-42A-12 does not show the flex seal. There were no open change documents posted against drawing EA-1S that removed the flex seal. In addition section 70-70 on drawing EC-32E-5 shows compressible materialinstalled in the shake spEce near the removable slabs ca the ESF Building Roof. If the flex seal at the t'ottom of the containment enclosure shown on EA-1S-1 or the compressible material shown on EC-32E-5 is installed, the ESF building does not appear to directly communicate with the containment enclosure.

2) NU Letter B14669 dated Novernber 4,1993, page 14 states that there is a SLCRS duct ccnnection for exhausting from the hydrogen recombiner building. Both P&lD EM-148E-12 and duct drawing EB 72A-6 show the exhaust duct openings blanked off and that damper 3HVR*DMP60 in the duct that exhausts from the sample room is normally closed. Therefore, there would be no direct SLCRS exhaust from the hydrogen recombiner building (bring secondary containment drawdown as implied in the letter.

3) As shown on P&lD EM-148E-12 and dvd swing EB 15M-10, SLCRS exhausts 6430 cfm from the conts oment enclosure at one location between columns C & D (auxiliary building side of the containment enclosure). Not all of the containment penetrations, shown on drawing EP-121 A-10 and EP-121B-8, are located in the same area (quadrant) Is the SLCRS exhaust opening in the containment enclosure. For example, the penetrations into the hydrogen recombiner building are on the opposite side of the enclosure. As the radius of the containment structure is ~75' exhaus+!ng from only one locatio1 does not ensure that leakage into the containment enclosure space is exhausted by SLCRS if thermal or wind effects cause the pressure differential to be less than 25 iwg in portions of the .

containment enclosure.

4) NU Letter B14669 dated November 4,1993, page 15, indicated that the combination of low outdoor temperatures and moderate wind speeds would occur less that 2% of the time. Based on FSAR Table 2.3-15, the 33-foot wind speed is between 4 - 12 mph 60.8% of the year and between 13 - 18 mph 18.77% of the year. Considering the containment structure as a cylinder, wind effects result in the pressure on the outside surface of the enclosure to vary significantly. With a 18 mph wind, the outside surface pressure for the containment enclosure varies from +0.15 iwg (O' azimuth) to -0.18 iwg (90' azimuth). A -0.25 iwg differential pressure reading at 0* azimuth would result in a +0.09 Pnnted 619/98 433.05 PM Page 6 of 8

• Northert Utilities ICAVP DR NL DR-MP3-0514 Millstone Unit 3 Discrepancy Report iwg differential at 90* azimuth. A -0.40 iwg differential pressure reading at O' azimuth would result in a -0.06 iwg differential at 90*

azimuth. Neglecting thermal effects that occur in the winter, using ,

a single measurement location could result in portions of the l secondary containment not meeting the differential pressure requirement of .25 iwg (outlined in IE-IN 88-76) more frequently

)

1 than the 2% of the timt stated in the letter.

5) Using an outdoor air temperature of 0*F and indoor air temperature of 50*F (ref, calc 92-071339-M3, CrN 001, pg 6) .

the differential pressure required at el 24'-6" to maintain the l

differential pressure at the top of the containment enclosure at - '

O.25 iwg is -0.51 iwg (ref, calc 92-071-339-M3, pg 10). The .40 iwg differential at el 24'-6" would meintain a .25 iwg differential {

with an outside air temperature of 20*F and an inside air temperature of 50*F. Note however, that based on New London, <

CT ASHRAE weather data, outside air temperatures are below  !

20*F more than 2% of the winter months. Therefore, to account for thermal effects only, the differential pressure at elevatiori 24'-

6" should be -0.51 iwg not -0.40 iwg.

This is considered a descrepant cond:liort riue to the following:

1. The -0.40 iwg differential pressure at elevation 24'-6" does not maintain the top of the containment enclosure at a .25 iwg j differential pressure when thermal effects described in NRC Information Notice No. 88 76 are accounted for.

2. Thc differential pressure at elevation 24'-6" in the auxiliary building has not been established as representative of the pressure in the containment enclosure and hydrogen recombiner building based on information received from NU.

3. The required differential pressure to offset normal wind effects on the containment enclosure has not been addressed.

Comments on Second and Supplemental Responses NU's response resolves ccmments #1 and 3 above. NU's response does not resolve comment #2 regarding the differential pressure measurement location.

1. The differential pressure is measured between the auxiliary building el 24'-O" and the service building. NU's response indicates that the service building door to the outside is opened during testing. This requirement was not contained in surveillance procedure SP36141.3 " Supplemental Leak Collection and Release System Negative Pressure Verification" until 4/2/98 when Change 3 issued. This is considered a discrepant condition as tests performed prior to 4/2/98 may have been influenced by the service building pressure relative to the outside.

2. The differential pressure measurement location does not bound the differential pressure in the main steam valve building in all cases. The B-train winter mode test results for IST 3-93-036 show the MSVB differential pressure as beloa 0.05 iwa less than tnat

' Pnrfled 6!1M8 4:33:05 PM Page 7 of 8

l - N:rthe st Utilities ICAVP DR N3. DR-MP3-0514 Millstone Unit 3 Discrepancy Report measured in the auxiliary building. The results of the May 30, 1995 Train B SLCRS Negative Pressure Verification show a differential pressure at elevation 24'-6"in the Auxiliary Building of -0.425 iwg at 120 seconds and -0.45 iwg at 200 seconds.

Adjusting for the 0.05 iwg offset in the MSVB, the secondary containment differential pressure is -0.375 iwg at 120 seconds and -0.40 iwg at 200 seconds which does not meet the acceptance criteria of 0.40 iwg within 120 seconds. The results of the May 30,1995 Train A SLCRS Negative Pressure Verification show a differential pressure at elevation 24'-6"in the Auxiliary Building (3HVR-PDl210) of -0.475 iwg at 120 seconds and -0.475 iwg at 200 seconds. The B-train results for IST 390-014 run #3 shows the MSVB 0.35 iwg ( .11 - ( .46)) less than the auxiliary '

building. The A-train results on run #1 show the MSVB 0.09 iwg (-

.41 - ( .5)) less than the audiary building. Therefore, using differential pressure measured at elevation 24'6" of the auxiliary building does not ensure that all areas of the secondary containment are drawn down to negative pressure within 120 i seconds after an accident as stated in FSAR Section 6.2.3.3.

3. The measurement location between the auxiliary building and service building (northwest comer) on elevation 24'6"is influenced by the charging pump room ventilation system (fans 3HVR*FN13A/B and 3HVR*FN14A/B). In the winter mode, air is l supplied to the component cooling pump area and exhausted through the charging pump rooms. In the summer mode, air is supplied and exhausted from the component cooling pump area (ref. drawing EB-45C-13). The net exhaust airflow in this area influences the differential pressure measured and may mask an lower differential pressure in the containment enclosure during drawdown testing.

This DR is unresolved.

This DR is being reissued as a confirmed level 4 discrepancy.

l We concur with NU that the issue regarding the fire stop and l seals (item id) is a level 4 discrepancy.

! We concur with NU that the use of the differential pressure measured at elevation 24'-6"in the auxiliary building for secondary containment drawdown time surveillance testing was approved by the NRC when Amendment 87 of the Technical Specification was issued. As NU is in compliance with the technical specification this is not a discrepant condition.

ver, as noted in our comments on the second and m.emental responses above, we do not concur that this single point measurement location is representative of the secondary containment differential pressure. This issue will be forwarded to the NRC.

Pmted 6/19/98 4 33 os PM Page 8 of 8 j

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e Northezt Utilitie3 ICAVP DR No. DR-MP3-0580 Millstone Unit 3 Discrepancy Report Review Group: Systern DR RESOLUTION ACCEPTED Review Elernent: system Design

[ PotentialOperabHity issue Dsscipline: Mechanical Design

( Discreg ancy Type: Ocensing Document @) Yes System / Process: HVX () No NRC Significance level: 4 Date faxed to NU:

( Date Published: 11/22/97 Discrepancy: Secondary Containment Drawdown with SLCRS and ABVS l

Description:

During review of the Supplementary Leak Collection and l

Release System (SLCRS) and the Auxiliary Building Ventilation System (ABVS) discrepancies regarding the required secondary containment drawdown time were identified.

Secondary containment drawdown requirements in the FSAR are:

FSAR Section 6.2.3.3 states that the SLCRS in conjunction with the auxiliary building filter system draws down the prescure to the minimum 0.4 inch negative pressure in 110 seconds from the time of emergency diesel generator breaker closure.

FSAR Section 6.2.3.3 states that the SLCRS and ABVS is required to drawdown the SLCRS areas to a negative pressure within 120 seconds after the accident. The negative pressure is measured at the Auxiliary Building 24-6 elevation and maintained per technical specifications at greater than or equal to 0.4 inches of water guage after a design accident.

FSAR Table 1.9-2, SRP 6.5.1 B.5 states that the SLCRS draws down enclosures contiguous to the containment to a minimum negative pressure of 1/4 iwg in 60 seconds after SIS.

SER Section 6.2.3 states that the capacity of the SLCRS is sufficient to reduce and maintain a pressure of -0.25 iwg throughout the e:alosure building and contiguous buildings within 1 minute after the accident, assuming a wind velocity of 22 mph.

The calculations that determine the secondary containment j drawdown time and SLCRS airflow are calculations:

P(B)-843, Rev. O Supplementary Leak Collection and Release l System l P(B)-1089, Rev. O Establish Acceptance Criteria for Air Leakage Through Pipe and Electrical Penetrations The objective of calculation P(B)-843 was to determine the required capacity of SLCRS and the time required for SLCRS to achieve a negative pressure of 0.25 iwg in the containment enclosure building and contiguous buildings. The results of the calculation indicate that with a 9,500 cfm SLCRS fan capacity the drawdown time to -0.25 iwg is 30 seconds. Review of the calculation identified the following discrepancies:

1. Calculation does not provide references for the building volume; usedh4he-calce!ctica ,

Printed 6/19/96 4:33:27 PM Page 1 of 13 1 I

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. Northrst Utilitie3 ICAVP DR No. DR-MP3-0580 Millstone Unit 3 Discrepancy Report

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2. Calculation does not adequately account for differences in air density between the outside air (infiltration into building) and at the inlet to the SLCRS exhaust fan. The air density at the 14n inlet is lower than the infiltrating air due to heat gains in the t'uilding and the electric heater in the SLCRS filter unit.

3. Assumes that fan flow is constant because the fan is equiped with variable inlet vanes. Neither P&lD EM-148E-12 nor specification 2176.430-141 show inlet vanes and associated controls for fans 3HVR*FN12A/12B. 1

4. Calculation does not address wind effects on leakage through i the containment enclosure. (

Calculation P(B)-1089 determines the allowable leakage rates and exhaust airflows for the areas exhausted by the SLCRS fans. Review of the calculation identified the following discrepancies:

1. Calculation determined that an exhaust rate of 130 cfm was required for the hydrogen recombiner building,4950 cfm for the containment enclosure building and 1350 cfm for the main steam valve building, P&lD EM-148E-12 shows the exhaust openings for the hydrogen recombiner building being blanked off, no airflow exhausted from the main steam valve building, and 6430 cfm exhausted from the containment enclosure.

2. Calculation does not address wind effects on leakage through l the containment enclosure. This results in under estimating the leakage through the containment enclosure.

In response to M3-RFI-00472 that requested the calculation (s) that determine the secondary containment drawdown time with the SLCRS assisted by the ABVS, NU in M3-lRF-00622 transmitted IST 3-93-45 and IST 3-93-46 which presented SLCRS and ABVS test data and calculation 92-071-339M3, SLCRS Drawdown Test Pressure Correction FaClor Calculation.

NU stated that the combination of these documents satisfies the request for the secondary containment draw down time with SLCRS and ABVS. Review of IST 3-93-045 SLCRS & ABVS Restest of PDCRs MP3-93-200 & 205 and IST 3-93-046 SLCRS

& ABVS Restest of PDCRs MP3-93-200 & 205 in Winter Mode from an engineering perspective identified the following discrepancies:

1. Plant conditions at time of the test did not correspond to postulated post-LOCA conditions. Therefore, not all heat loads that would be present during the postulated accident were present. The tested drawdown time needs to be adjusted to address areas such as the main steam valve building that have the non-safety ventilation system that provides cooling during normal plant operating isolated on a SIS. Due to differences in heat gains present during test and accident conditions the tested draw down time will be faster than the accident condition time.

Pnnted 6/19/98 43326 PM PaDe 2 of 13

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. Northext Utilities ICAVP DR No. DR-MP3 3580 l

l Millstone unit 3 Discrepancy Report

2. Test did not record differential pressures and times for the recombiner building which is inside the secondary containment boundary.

3. Test results do not identify SLCRS or ABVS system airflows during test. Technical Specification 4.6.6.1 states that the SLCRS is considered operable witn a flow rate of 7600 cfm to 9800 cfrn. Results need to be adjusted to correspond to minimum airflow conditions since the draw down time is directly affected by the SLCRS airflow rate.

3. The acceptance criteria of a 2.5 minute drawdown time to 0.4 iwg negative pressure in IST 3-93-045, Rev. O, Change 7 and IST 3-03-046 Rev. O, Change No.1 do not agrea with FSAR drawdown times show above.

NU letter B15028 dated December 14,1994 submitted a proposed revision to Technical Specifications for the Supplementary Leak Collection ar.d Release System. The proposed Section 4.6.6.1.d.3 Surveillance Requirement is

Verifying that each system produces a negative pressure of greater than or equal to 0.1 inch Water Guage in the Auxilia;y Building at 24'6" elevation within 60 seconds after a start signti and a negative pressure of greater than or equal to 0.4 inches Water Guage in the Auxiliary Building at 24'6" elevation within the next 120 seconds." On page 6 of the letter NU states "With 4 the proposed negative pressure criteria for the secondary {

containment it could be assurrmed that ail leakage into the i

becondary containment is filtered, since a sufficient negative pressure is achieved within one minute and the final required negative pressure is acheived within the next two minutes."

When the difference between accident and test heat loads, wird effects, and cortuction factor for the measured differential pressure are accounted for, not all areas within the containment enclosure will be at a negative pressure within 60 seconds.

Other Discrepancy Reports that address related issues:

DR-MP3-0514 Containment Enclosure Building Negative Pressure DR-MP3-0030 Drawdown Times for Rod Ejection Accident and 1 1

LC %

Review ,

Valid invalid Needed Date l Initiator: stout, M. D. O O O 10/24/97 VT Lead: Nerl. Anthony A B O O 10'31'S7 VT Mgr: schopfer. Don K B O O 11'S'S7 IRC Chmn: singh. Anand K B O O 11/18/97 Date:

INVAUD:

Date: 5/29/98 RESOLUTION: First Response NU has co uded that the issues reported in Discrepancy Pnnted 6/19/98 4.3328 PM Page 3 of 13 L_-_____________

Northert Utilities ICAVP DR No. DR-MP3-0580 l* Millstone Unit 3 Discrepancy Report l

Report, DR-MP3-0580, do not represent discrepant conditions.

DR-MP3-580 identifies issues with regard the Secondary Containment drawdown times provided in the FSAR, Technical Specifications and design calculations.

FSAR Section 6.2.3.3 The referenced FSAR Section 6.2.3.3," Safety Evaluation,"

provides a description of the Secondary Containment drawdown requirements. The statements regarding the drawdown times have been reviewed per the CMP Annotation Process and are correct and consistent with the Technical Specifications.

Therefore, no FSAR changes with respect to drawdown times are required.

Amendment No. 87 issued on 12/8/93 changed the Technical Specifications to increase the required drawdown time from 60 seconds to 120 seconds and increased the required negative prest.ure of 0.4 in. wg, Amendment 10 issued on 8/24/87 changed the Technical Specifications to increase the emergency diesel startup time from 10 seconds to 11 seconds to avoid declared diesel generator failures for fractions of a second beyond 10 seconds.

The Amendment No.10 changes do not impact the ESF response time requirements. In addition, Technical Specification Bases, Section 4.6.6.2 states that the time to achieve the required negative pressure is 120 seconds, with a loss-of-offsite power coincident with a SIS. Therefore, the 110 seconds from the time of emergency diesel generator breaker closure plus the emergency diesel startup time is correct and consistent with the total drawdown time of 120 seconds.

FSAR Table 1.9-2, SRP 6.5.1.B.5 The statements in this section were compiled for use by the NRC for review during the request for FTOL stage for MP3. FSAR Section 1.9 and the associated tables are considered historical in nature and are not updated. FSARCR 97-MP3-95 was initiated as a result of the CMP FSAR Annotation process to clarify FSAR Section 1.9 as historical. FSARCR was completed on 6/30/97.

SER Section 6.2.3 The MP3 Safety Evaluation Report (NUREG-1031) was issued on 8/2/84 by the NRC Amendment No. 87 issued on 12/8/93 changed the Technical Specifications to increase the required drawdown time from 60 seconds to 120 seconds and increased the required negative pressure from 0.25 in. ';sg. to 0.4 in, wg.

Amendment 87 supersedes SER, dated 8/2/84, section 6.2.3 with regard to drawdovai time and required vacuum.

Calculation P(B)-843 CR M3-97-2187 was initiated on 7/t 4/97 to track potential FSAR deficiencies which were identified during the CMP FSAR annotation process. CR M3-97-2187 corrective action plan required calculation P(B)-843 to be revised. CCN 01 to calculation P(B)-843. Rev. O. was approved on 10/30/97 and Pnnted 6/1D/98 4:3328 PM Page 4 of 13

. N::rthext Utilitie3 ICAVP DR No. R-MP3-0580 Millstone Unit 3 Discrepancy Report closed CR M3-97-2187. CCN 01 states that the SLCRS is a unique system in that its sizing is not based on rigorous methodology. To do so would require postponing the des:gn until construction is complete and then a rigorous analysis would determine its capacity based on "as constructed" leakage paths, concrete cracks, vendor data, etc. To avoid such delays, secondary containment leakage determination is based on " rule of thumb" design criteria derived form previous experience. The criteria adopted on Millstone Unit 3 were three volume changes per day for the containment enclosure and one volume change per day for the balance of the secondary containment. A rigorous computation and system analysis is unwarranted considering the uncertainty of the basic design input. The installed equipment is periodically tested and proven to the defined operating parameters. Therefore, the initial design capacity information in calculation P(B)-843 is considered historical and no additional changes to calculation P(B)-843 are required. I Note that the variable inlet vane is manually fixed by the vendor supplied lever. The vendor drawings 12179-2170.430-002G and 12179-2170.430-004 showing the fan, VIV and lever control.

Calculation P(B)-1089

1) DR MP3-509 and DR-MP3-560 have identified similar issues regarding the presentation of P&lD general area exhaust flow I paths and calculation P(B)-1089. The following is the response to DR-MP3-509 which applies to item 1 of calculation P(B)-1089 issues in DR-MP3-580.

DR-MP3-0509 identifies that P&lDs EM-148E, EM-148A, and EM-1528 do not provide the general area exhaust flow paths required to maintain the Secondary Containment under a negative pressure following a LOCA. The format and content of the MP3 P&lDs are established in procedure EDI 30255, *MP5 Piping and instrumentation Diagrams Detailed instructions for Format and Content." EDI 30255 does not require MP3 P&lDs to reflect the actual building arrangement. The P&lDs provide the systems configuration required to maintain the Secondary Containment under a negative pressure following a LOCA. The P&lDs are not required to provide general area exhaust flow rates, therefore, changes to P&lDs EM-148E, EM-14BA, EM152B -

are not required.

The Secondary Containment is comprised of the containment enclosure building, the auxiliary building, and sections of the s,ngineered safety features building, the main steam valve building, and the hydrogen recombiner building. The interior walls of the engineered safety features building, the main steam valve building, and the hydrogen recombiner building which separate the areas contiguous to the containment from the j remainder of the buildings serve as the secondary containment boundary. The areas that are not directly exhausted by an exhaust duct and registers located within the area are interconnected with adjacent areas that contain exhaust ducts and reaisters. The Secondary Containment Boundaries are Pnnted 6/19/90 4:3328 PM Page sof 13

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. N:rthert Utilities ICAVP DR No. DR-MP3-0580 Millstone Unit 3 Discrepancy Report identified on S&W EM-60 series drawings, " Plant Fire Radiation and Pressure Boundaries." The areas of the hydrogen recombiner building that contain the capped off ducts are not part of the Secondary Containment Boundary The areas of the main steam building and hydrogen recombiner building that are within the Secondary Containment boundary are drawn down through the enclosure building by the SLCRS.

Calculation P(B)-1089,

• Establish Acceptance Criteria for Air Leakage Through Pipa and Electrical Penetration Saals,"

provides a summary table for the exhaust flow rates for the applicable areas. The summary table shows the exhaust flow rate for the containment enclosure building as 4950 cfm, the j hydrogen recombiner building as 130 cfm and the main steam l valve building as 1350 cfm. P&lD EM-14BE indicates the total exhaust flow from these areas through the 36" X 18" screened  ;

opening as 6430 cfm. '

As an enhancement, CR M3-974557 was initiated to clarify the air flow rates on all of the MP3 P&lDs. CR M3-97-4557 corrective action requires a review of all air flows and notes on HVAC P&lDs, related Technical Specifications, and FSAR Sections. Based on the evaluation results, the P&lDs will be revised to include clarifying notes or remove air flow information and revise EDI 30225, if required.

2)The containment enclosure was purchased under Specification 2190.371-442. The Specification addresses wind effects on leakage through the enclosure building by assuming a 22 MPH wind at .0195 cfm/ft2. The wind effects result in a total allowable leakage of 2,830 cfm for the enclosure building. The containment enclosure leakage was not computed in calculation P(B)-1089, as stated on page 9. With the wind effects addressed in the specification, no changes to the calculation are required.

IST 3-93-45 and 3-93-46 1)The heat gain in the MSVB and other areas of the Fa" ary Containment during the first 120 seconds post L 'r, Les not hoe a significar.t impact on the test results. The swdown test is typically performed during refueling outages but has been performed at 100% power. The test results are not significantly different between the testing during refueling outage and the testing during 100% with the MSVB ventilation system isolated.

Therefore, the test method and results are satisfactory.

2) The area the hydrogen recombiner building that is within the Secondary Containment boundary is shown on the S&W EM-60 series drawings. This area is drawn down throcgh the encibsure building by tne SLCRS. SER to Amendment No. 87 concludes that SLCRS (with ABVS) is capable of adaining the required negative pressure of 0.4 in. wg. 'within 120 seconds and that utilizing the single measurement location in the auxiliary building a the 24' 6" level is suitable.

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, N:rthesnt Utilities ICAVP DR No. DR-MP3-0580 Millstone Unit 3 Discrepancy Report i

3)SLCRS and ? BVS airflows are taken once a month to verify fan performance per SP 36141 and SP 3614A. The drawdown test is a functional test of the system and a verification of boundary integrity. There is no requirement to adjust the drawdown time to correspond to the minimum air flow rate.

Technical Specification Bases, Section 4.6.6.2.2 states that since SLCRS fan flow rates are verified to be acceptable on a more frequent basis than the drawdown test surveillance, and by means of previous testing the minimum flow rate l's acceptable, verifying a flow rate during the drawdown test would not provide i an added benefit.

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4) Acceptance criteria of these tests were based on a proposed j licensing change. The proposed licensing change was amended  !

to a 2 minute drawdown after the tests were completed. The change to the 2 minute drawdown was based on the test results j meeting the required negative pressure of 0.4 in. wg. criteria l within 2 minutes.

SER for Amendment No. 87, dated 12/8/93, concludes that I SLCRS (ABVS)is capable of attaining the required negative pressure of 0.4 in. wg. within 120 seconds based on the test results.

PTSCR 3-16-94, dated 12/14/94 I The last paragraph in DR-MP3 580 describes a proposed I revision to TS. This revision to the Technical Specifications is I being reviewed by the NRC, therefore, is not part of MP3 license.

Attachments:

CCN 01, Calculation P(B)-843. Rev. O CR M3-97-2187 1 Second Response (M3-lRF-02108)

NU has concluded that item 3 in Discrepancy Report DR-MP3-0580 has identified a condition not previously discovered by NU which requires correction.

(3) Secondary containment Leakage determination,is based on industry standard design criteria derived from previous experience. The criteria adopted on Millstone Unit 3 were three (3) Volume changes per day for the Containment Enclosure and one Volume change per day for the balance of the secondary Containment. This criteria was taken from calculation P(B)-843 and used as conceptual input in calculation P(B)-1089.

Therefore, Calculation P(B)-1089 is considered conceptual to establish pre-construction acceptance criteria for ellowable air i leakage through different types of pipe and electrical penetration seals. The penetration seals vendor applied a conservative

factor of safety to the results of calculation P(B)-1089 and lab tested the seals before and after completion of construction under stringent acceptance criteria. Hence, a rigorous revision of such Conceptual calculation and system analysis is unwarranted considering the uncertainty of the basic desian input. NU hat

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N:rthert Utilities ICAVP DR No. DR-MP3-0580 l .

l Millstone Unit 3 Discrepancy Report 1

i written CR M3-98-1774 to clarify this point. The approved I corrective action will initiate a CCN to change the status of l calculation P(B)-1089, Rev. 00 to " Historical Calculation".

NU has concluded that items 2 and 4 of Discrepancy Report DR-MP3-0580 do not represent discrepant conditions. .

l (2) In-Service Test No. IST 390-014, (copy attached) which is per Surveillance procedure SP 36141.3, was performed successfully on 7/20/90 (at that time the Plant was in Mode 1 of .

operation). The objective of this test was to verify that the I SLCRS Negative Pressure Verification Test could be performed I to satisfy its acceptance criteria of producing a negative pressure equal to or more negative than (-)0.25 inches W.G. within 50 seconds after a start signal, with flow through the SLCRS system throttled to 6,800 to 7,200 CFM which is below the flow rate range of 7,600 to 9,800 CFM mandated by Technical '

Specification.

The successful conclusion of this test resulted in a Tech. Spec.

change to the flow rate acceptance criteria. The objective of NUREG 0800, USNRC Standard Review Plan and associated Branch Technical Position CSB 6-3 B.3, is to provide guidelines for licensing the operation of the Plant. The NRC does not mandate compliance with this Branch Technical Position, nor did it require verification of drawdown by analysis as a condition l for licensing in 1985. Nevertheless, as stated above, drawdown at flow rates less than the minimum of the current Technical Specification was verified by test Monthly flow tests aie performed to monitor fan performance in accordance with Td 4.6.6.1. The drawdown test is performed to verify bouridary integrity is maintained in accordance with TS 4.6.6.2. There is no requirement to perform flow rate testing during the drawdown test.This item is, therefore, considered non-discrepant.

(4) The ot,Jective of CCN 1 is to make calculation P(B)-843 a historical document which has served its purpose in sizing the SLCRS drawdown capability using criteria derived from industry practice and previous experience. The system has since been installed, tested, and verified to be adequate for its intended purpose. NUREG-0800, USNRC Standard Review Plan and associated Branch Technical Position CSB 6-3 8 3, provide guidelines for licensing the operation new plants. Therefore, pressure response analysis per NUREG-0800 for a system which has been tested successfully is not required. This item is considered non-discrepant.

The discrepancy reported in item 3 will be corrected post startup per the approved corrective action plan for CR M3-98-1774.

Licensing basis and design basis are not affected; therefore, NU considers this issue Significance Level 4.

Attachments:

CR M3-98-1774 with approved corrective action plan IST 390-014, 7/20/90 Printed 6/19/98 4.33% PM Page 8 of 13

- Northeast Utilities ICAVP DR No. DR-MP3-0580 Millstone Unit 3 Discrepancy Report Previously identified by NU? (.) Yes (*) No Non Discrepant Condition?( ) Yes (#) No ,

Resolution Pending?O ve. (*) No

. Resolution Unresolved?O ve. C*)No Review l Acceptable Not Acceptable Needed Date Initiator: stout, M. D.

VT Lead: Neri, Anthony A VT Mgr: schopfer, Don K IRC Chmn: Sis y , Anand K l

Date: 5/29/98 sL Comments: Comments on First Response j 1

1. Agree with NU's response that FSARCR 97-MP3-95 identifies i FSAR Table 1.9-2 as historical data and that that SER for Amendment No. 87 supersedes SER (,ated 8/2/1984.

2. The secondary containment drawdown time is a function of the boundary leakage, building volume, heat gain the the building, and the exhaust flow rate. One set of surveillance tests verifies SLCRS and ABVS airflows are within limits and another set of surveillance tests verifies that secondary containment drawdown time is less than or equal to 120 seconds. Neither of the tests ,

establish the secondary containment boundary leakage as stated i in Branch Technical Position CSB 6-3 B.3. Since drawdown tests I do not measure the SLCRS and ABVS airflows the ability of the SLCRS and ABVS systems to drawdown the secondary containment within 120 seconds at the lowest Technical Specification allowable airflows is not verified by test nor analysis.

NU's response should address why they do not consider this to be a discrepant condition.

3. Calculation P(B)-1089 determines the allowable leakage rates and exhaust airflows for the areas exhausted by the SLCRS fans.

The results of calculation P(B)-843 are used as input for establishing the exhaust flow rates. Calculation P(B)-1089 needs to be revised to address the use of unverified data from

" historical" calculation P(B)-843, CCN1,

4. Calculation P(B)-843, CCN 1 states that the secondary containment leakage criteria adopted for Millstone 3 was three volume changes per day for the containment enclosure and one volume change per day for the balance of the secondary containment. The CCN does not provide adequate justification for not performing the ;;ressure response analysis identified in Branch Technical Position CSB 6-3 B.2 and B.4.

Comments on Second Response

References:

1) FSAR Section 6.2.3.3

2) Technical Specification Amendment No. 87 issued 11/4/1993 (revision for surveillance 4.6.6.1.d.3)

3) NU Letter B14669 dated 11/4/1993

4) 14U Letter B15424 dated 11/9/1995

5) SP 36141.3 SLCRS Negative Pressure Verification - Train B Pnnted 6/19/98 4:3329 PM Page 9 of 13

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, N:rthea::t Utilities ICAVP DR No. DR-MP3-0580 Millstone Unit 3 Discrepancy Report test results dated 5/30/1995 l

6) SP 36141.1 SLCRS Operability Test - Train B test results dated j 1/23/1998

7) IST 390-014 test results dated 7/20/1990

8) P&lD EM-148A-24

9) P&lD EM-148B-15 .

10) P&lD EM-148E-12 j

11) Technical Specification bases section 3/4.6.6.1

12) Technical Specification bases section 3/4.6.6.2 I

13) Technical Specification bases section 3/4.7.9

14) SLCRS Negative Pressure Verification - Train B test results dated 10/4/95 (retest for ACR 005188)

Disagree with NU's response. j l

The run #1 (A Train) results of IST 390-014 show that the Main Steam Valve Building (MSVB) differential pressure is -0.41 iwg and Aux. Bldg el 24'-6" differential pressure is > -0.5 iwg (off scale) at 50 seconds. The run #3 (B Train) results show that the MSVB differential pressure is -0.11 iwg and Aux. Bldg el 24'-6" differential pressure is > -0.5 iwg (off scale) at 50 seconds. As the MSVB differential pressure is more representative of the containment enclosure differential pressure, the B Train drawdown test does not support the conclusion that at a SLCRS airflow of 7200 cfm that the .25 iwg differential pressure within 50 seconds (acceptance criteria in effect when test was run) was met. The results of this test also do not support the conclusion that the current drawdown requirement of -0.40 iwg within 120 seconds could be met with the minimum SLCRS airflow of 7600 cim.

The results of SP36141.3 SLCRS Negative Pressure Verification -

Train B test conducted on 5/30/95 show an Aux Building differential pressure of -0.25 iwg at 50 seconds and -0.425 iwg at 120 seconds. The system airflows for this test are not known as they were not measured. If they are comparable to the 8811 scfm measured on 1/23/98 during performance of SP 36141.1 SLCRS Operability Test - Train B it is not apparent that the 120 second drawdown time could be achieved with the Technical Specification 4.6.6.1.a minimum SLCRS airflow of 7600 cfm.

Note 2 on P&lD EM-148E 12 states that SLCRS operability is demonstrated by Technical specification surveillance flows of 7,600 to 9,800 cfm.

The drawdown time is a function of the secondary containment boundary leakage and the SLCRS and ABVS airflow rates. NU Letter B155424 dated November 9,1995 responds to a NRC Staff question during a October 4,1995 conference call as to why NNECO was not specifying a maximum allowable flow rate in the

Secondary Containment drawdown surveillance requirement (i.e.,

Surveillance Requirement 4.6.6.1.d.3 which is being relocated to l

Specification 3.6.6.2 Secondary containment). NU's response in this letter states in the 3rd paragraph on page 2 'The SLCRS system and fan sizing was based on an estimated infiltration rate.

y The fan flow rates are verified within a minimum and maximum on a monthly basis. Initial testina verified that the drawdown Pnnled 6/19,98 4:33:29 PM Page 10 Of 13

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- Northeast Utilities ICAVP DR Ns. DR-MP3-0580 Millstone Unit 3 Discrepancy Report l

criteria was met at the lowest acceptable flow rate. Surveillance Requirement 3.6.6.12 of the new standard Technical Specif: cation (NUREG-1431) requires that the drawdown criterion be met while not exceeding a maximum flow rate, it is assumed that the purpose of this flow limit is to ensure that adequate attention is given to maintaining the SLCRS (secondary containment) boundary integrity and not using excess system capacity to offset boundary degradation." The 4th paragraph on page 2 states "The SLCRS system was designed with minimal margin; therefore it does not have excess capacity that can be substituted for boundary integrity. Additionally, CLCRS fan flow rates are verified to be acceptable on a more frequent basis than the drawdown test surveillance. Previous testing of the minimum flow rate is acceptable, thus verifying a flow rate during the drawdown test would not provide an added benefit. Historical SLCRS flow measurements show a lack of repeatability associated with the inaccuracies of air flow measurement. As a result, the more reliable verification of system performance is the actual negative pressure generated by the drawdown test and a measured flow rate would add little benefit."

NU letter B155424 does not address the impact that the Charging Pump and Component Cooling Water Pump Area fans (3HVR*FN13A/B and 3HVR*FN14A/B) and Auxiliary Building Ventilation Filter exhaust fans (3HVR*FNBA/B) have on Secondary Containment drawdown time. Fans 3HVR*FN6A/B,

• FN13A/B, and *FN14A/B operate in conjunction with SLCRS exhaust fans 3HVR*FN12A/B to drawdown the secondary containment. The amount of outside air supplied by fan 3HVR*FN14A/B is seasonally adjusted by repositioning dampers 3HVR*DMP4 and 3HVR*DMP32 twice a year per note 17 on P&lD EM-148A. The summer and winter mode positions are marked on the dampers used to change the system from summer to winter mode. The net exhaust (outside air supply - exhaust) airflow used to assist the SLCRS in the drawdown of the secondary containment is not measured on a regular basis as part of a Technical Specification Surveillance. Changes in this net exhaust airflow could mask degradation of secondary containment if the airflow is not known during the drawdown test.

Technical Specification surveillance requirement 4.6.6.2.2 states "At least once each refueling interval, verify that each Supplementary Leak Collection and Release System produces a negative pressure of grester than or equal to 0.4 inch water gauge in the Auxiliary Building at 24'-6" elevation within 120 seconds after a start signal."

Technical Specification surveillance requirement 4.6.6.1 requires a SLCRS airflow rate between 7600 cfm to 9800 cfm is verified at least once every 31 days on a staggered test basis.

Therefore, measurement of the SLCRS & ABVS airflow rates during drawdown time surveillance testing and evaluation of the results is necessary to verify that the drawdown time stated in FSAR Section 6.2.3.3 and used in the offsite dose analysis can be met at the lowest desian SLCRS airflow rate of 7600 cfm.

Printed 6/19/98 4 33:30 PM Page 11 of 13

- Northeast Utilities ICAVP DR No. DR-MP3-0580 Millstone Unli 3 Discrepancy Report Measurement of the outside airintake and exhaust airflows associated with auxiliary building fans 3HVR*FN06A/B, 3HVR*FN13A/B, and 3HVR*FN14A/B is also needed to verify that variation in the auxi;iary building ventilation system exhuast air to outdoor air differential airfow (resulting from annual summer / winter mode changeover) do not mask degradation of secondary containment integrity.

The DR is unresolved.

This DR is being reissued to clarify the issues that are confirmed discrepancies.

We concur with NU that the current secondary containment drawdown test, which does not specify system airflows, was accepted by the NRC when Amendment 87 of the Technical Specification was issued. As NU is in compliance with the technical specification this is not a discrepant condition.

CCN 1 to calculation P(B)-843 was issued as part of the corrective action of CR TA3-97-2187. CCN 01 states "SCRS is a i unique system in that its sizing is not based on rigorous I methodology. To do so would require postponing the design until construction is complete and then a rigorous analysis would detennine its capacity based on 'as constructed' leakage paths, concrete cracks, vendor data, etc. To avoid such delays, secondary containment leakage determination is based on ' rule of thumb' design criteria derived form previous experience. The criteria adopted on Millstone Unit 3 were three volume changes per day for the containment enclosure and one volume change l per day for the balance of the secondary containment. A rigorous computation and system analysis is unwarranted considering the uncertainty of the basic design input. The installed equipment is l periodically tested and proven to the defined operating parameters. Therefore, this calculation is historical in nature" The corrective action of CR M3-98-1774 states

• Review MP3 calculation P(B)-1089 ' Establish Acceptance Criteria for Air Leakage Through Pipe and Electrical Penetration Seals' and calc.

P(B)-843 ' Supplemental Leak Collection and Release System'.

Reverify that the data contained within calc. P(B)-1089 is historical in nature, add justification addressing inputs taken from calc. P(B)-843 and revise as such with a reference tie in the body l of the calculation, as well as in the Calculation Tracking Program i input sheet to calc. P(B)-843." The deferraljustification for CR M3- l 98-1774 states "The revision to calculation P(B)-1089 will provide  ;

justification that it is an h storical calc. in nature and provide a reference and program tie to calc. P(B)-843. Both calculation were initial conceptual plant design calculations and can be considered historical in nature. The Integrity of the Secondary Containment and penetration bypass leakage is periodically verified by Tech Spec. Surveillance's and Inservice inspections.

The information contained in calculation P(B)-1089 does not affect any plant procedure, the operation of any plant twtem or eauipment affect Tech Spec requirements or system aesian Pnnted 6/19/98 4:33 30 PM Page 12 of 13 l

L

. N:rthea:t Utilities ICAVP DR No. DR-MP3-0580 Millstone Unit 3 Discrepancy Report basis or operation as described in the FSAR."

Based on the periodic surveillance tests meeting the technical specification requirements, the corrective actions for calculations P(B)-843 and P(B)-1089 resolve level 4 discrepancies.

However, we do not concur that the Technical Specification surveillance requirements are adequate to ensure that secondary containment boundary leakage is within design limits and the SLCRS in conjunction with the ABVS system will meet its drawdown time requirements under accident conditions. This issue will be forwarded to the NRC.

t Prrted 6/19/98 4.33.30 PM Page 13 of 13 l

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