ML040770217
| ML040770217 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 01/31/2004 |
| From: | Mccutchen E Nebraska Public Power District (NPPD) |
| To: | Michelle Honcharik Office of Nuclear Reactor Regulation |
| Honcharik M, NRR/DLPM, 301-415-1774 | |
| Shared Package | |
| ML040820923 | List: |
| References | |
| GL-96-006 | |
| Download: ML040770217 (6) | |
Text
Michelle Honcharik - GL 96-06 Safety Evaluation Clarification' Letier-Page 1 i From:
"McCutchen, Edward L." <elmccut@nppd.com>
To:
"Michelle C. Honcharik (E-mail)" <mch3@nrc.gov>
Date:
1/31/04 4:27PM
Subject:
GL 96-06 Safety Evaluation Clarification Letter
- Michelle, Attached please find the draft of the letter we discussed Friday about the 3 minor clarifications in Section 3.1 of the SE. Please ask your tech reviewers to look these over and advise if there is any problem from their perspective. Thanks!
<<2004011.doc>>
Best Regards, Edward (Ed) L. McCutchen, Jr.
Licensing Supervisor, Cooper Nuclear Station (402) 825-2707 office, (402) 943-0921 pager
\\4ichelle Honcharik - 2004011.doc P~a g e 1 I F-i NLS200401 1 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001
Subject:
Clarification of Generic Letter 96-06 Safety Evaluation Cooper Nuclear Station NRC Docket 50-298, DPR46
References:
- 1.
Nebraska Public Power District letter to the U.S. Nuclear Regulatory Commission dated June 9, 2003, "Response to NRC Generic Letter 96-06"
- 2.
U.S. Nuclear Regulatory Commission letter to Nebraska Public Power District dated November 3, 2003, "Cooper Nuclear Station (CNS) - Final Closeout of Responses to Generic Letter 96-06 (TAC NO. M96799)"
The purpose of this letter is to clarify statements made in the safety evaluation issued by the U.S.
Nuclear Regulatory Commission (NRC) documenting resolution of Generic Letter 96-06 for the Cooper Nuclear Station (CNS). By Reference 1 Nebraska Public Power District (NPPD) submitted final responses to resolve Generic Letter 96-06 for CNS. By Reference 2 the NRC documented their approval of the responses from Reference 1 through issuance of a safety evaluation (SE). NPPD has reviewed that SE and has identified three statements that it considers should be clarified. The clarification is attached.
NPPD believes that this clarification does not invalidate the NRC conclusions documented in the SE. As discussed with the NRC Project Manager this letter is sufficient to resolve these items, without the need for the NRC to formally revise the SE.
If you have any questions regarding this issue please call me at (402) 825-2774.
Sincerely, Paul V. Fleming Licensing and Regulatory Affairs Manager
/rer Attachments
M~ichelle Honcharik - 200401 1.doc Page 2 11 Michelle Honcharik - 2004011.doc Page 2 NLS200401 1 Page 2 of 2 cc:
Regional Administrator w/ attachments USNRC - Region IV Senior Project Manager w/ attachments USNRC - NRR Project Directorate IV-1 Senior Resident Inspector w/ attachments USNRC Nebraska Health and Human Services w/ attachments Department of Regulation and Licensure NPG Distribution w/o attachments Records w/ attachments
Michelle Honcharik - 2004011.doc Page 3 "
NLS200401 1 Page 3 of 2 9WA Attachment Clarification of Generic Letter 96-06 Safety Evaluation Cooper Nuclear Station Nebraska Public Power District
- 1. A statement in the Generic Letter (GL) 96-06 Safety Evaluation (SE) regarding closure of isolation valves in the Reactor Equipment Cooling (REC) System needs clarification. SE Section 3. 1, second paragraph, first sentence, states:
"Following a LOOP, the REC pumps will stop and the isolation valves between the REC pumps and the drywell FCUs will close on reduced system pressure."
This sentence correctly reflects that following a Loss-of-Offsite Power (LOOP) the REC pumps will stop and that pressure in the REC System will drop. The clarification is that the low pressure in the REC System sends a signal to the isolation valves to close, but that the valves are electrically powered and do not actually close until the bus is re-energized, either by start of a diesel generator or restoration of offsite power.
An appropriate revision of the SE would be to end the sentence by adding the words "when re-energized."
- 2. A statement in the SE appears to indicate a potential misunderstanding on the part of the NRC staff regarding how drywell spray is actuated at CNS. NPPD wishes to correct any such misunderstanding that might exist or arise. SE Section 3.1, second paragraph, fourth sentence, states:
"A small MSLB might not cause drywell spray to actuate, resulting in elevated containment temperatures and subsequent voiding in the containment FCUs."
NPPD believes that this sentence could be interpreted to mean that drywell spray actuates automatically. The drywell spray at CNS does not actuate automatically. Rather, it is actuated manually by operators when appropriate conditions exist, as directed by the Emergency Operating Procedures (EOPs).
Initiation of drywell spray was discussed in the third paragraph of the NPPD response to GENERIC LETTER 96-06 Issue No. 2 in Attachment 3. That response stated that EOP 3A (Emergency Procedure 5.8) directs all available drywell cooling be operted in the event that average drywell temperature cannot be maintained below 150'F, and further directs drywell spray be initiated before average drywell temperature reaches 2800F. This statement implies that drywell spray is initiated by operator action (i.e. manually), as directed by EOP 3A.
NPPD wishes to correct this possible misunderstanding since it conflicts with the CNS design basis and could result in possible confusion in the future and documenting this in the CNS
Michelle Honcharik - 2004011.doc NLS2004011 Page 4 of 2 Corrective Action Program.
Page 4j]
An appropriate revision of the SE would be to have the sentence state: "A small MSLB might not cause drywell spray to be initiated by operators immediately, resulting in..."
- 3. A statement in the SE regarding the opening time for an isolation valve in the REC System contains a minor difference from what was stated in the NPPD submittal. SE Section 3.1, second paragraph, next to last sentence, states:
"In actuality, the isolation valve downstream of the REC pumps has a long opening stroke of 32 seconds."
In Attachment 1 of the NPPD submittal, the response to NRC Request number 4 stated:
"In addition, the opening stroke time of approximately 32 seconds for valve REC-MOV-702 will result in an initial slow flow that will slowly sweep away the voids."
Stating the valve closure time in the SE as a specific "32 seconds" rather than as "approximately 32 seconds" could cause a reader to think that the closure time must be exactly 32 seconds. It is likely that the valve opening time would not be an exact 32 seconds.
Discovery of a closure time for this valve that is not exactly 32 seconds might be considered as a condition that is in conflict with the SE and result in the condition being entered into the CNS Corrective Action Program.
As stated in the NPPD submittal, and reflected in the NRC SE, the basis for the CNS configuration being acceptable is that the closure time for this valve be sufficiently long for voids in the coils of the Fan Coil Units to be swept away by the flow with minimal potential for waterhammer. Although a specific range of acceptable valve opening times cannot be specified, a stroke time slightly less than 32 seconds is acceptable, or any time longer than 32 seconds would be acceptable with respect to minimizing the potential for waterhammer.
Stating that the valve has a long opening stroke time adequately conveys the principal consideration that the stroke time must be long enough in duration to allow voids to be condensed slowly. The time of 32 seconds (or "approximately" 32 seconds) is not critical to minimizing the potential for waterhammer. Thus, NPPD suggests that reference to any stroke time be deleted.
An appropriate revision of the SE would be to revise the sentence to state: "In actuality, the isolation valve downstream of the REC pumps has a sufficiently long opening time."
C=TEMP\\WiW001.TMPP Page 1 11 Mail Envelope Properties (401CID92.196:16: 4502)
Subject:
Creation Date:
From:
Created By:
GL 96-06 Safety Evaluation Clarification Letter 1/31/04 4:26PM "McCutchen, Edward L." <elmccut@nppd.com>
elmccut@nppd.com Recipients nrc.gov owf4_po.0WFNDO MCH3 (Michelle Honcharik)
Post Office owf4_po.0WFNDO Route nrc.gov Files MESSAGE 200401 1.doc Mime.822 Options Expiration Date:
Priority:
Reply Requested:
Return Notification:
Concealed
Subject:
Security:
Size 406 34304 48891 Date & Time 01/31/04 04:26PM None Standard No None No Standard