ML20209F503
| ML20209F503 | |
| Person / Time | |
|---|---|
| Issue date: | 01/30/1987 |
| From: | Jordan E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Pickens T BWR OWNERS GROUP, NORTHERN STATES POWER CO. |
| References | |
| IEB-85-003, IEB-85-005, IEB-85-3, IEB-85-5, NUDOCS 8702050117 | |
| Download: ML20209F503 (6) | |
Text
1 JAN 3 01987 Mr. Terrance A. Pickens, Chairman BWR Owners' Group Northern States Power 414 Nicollet Mall Minneapolis, Minnesota 55401
Dear Mr. Pickens:
Your letter of September 2,1986, forwarded copies of NEDC-31322, "BWR Owners' Group Report on the Operational Design Basis of Selected Safety-Related Motor-0perated Valves." This report was to be used by the member utilities as a basis for the selection of valves and their maximum expected differential pressures in preparation of their responses to IE Bulletin 85-05, " Motor-Operated Valve Common Mode Failures During Plant Transients Due to Improper Switch Settings."
In my letter of October 10, 1986, I informed you of the results of a prelimi-nary review which indicated that the criteria used in the GE Owner's Group report appeared to conflict with the bulletin requirement to consider
... inadvertent valve closures or openings...."
The formal review of the GE Owners' Group report has been completed. The detailed comments, including those pertaining to the above noted conflict, are enclosed.
It is requested that you notify your member utilities of our comments, revise tac GE Owners' Group report to address the concerns raised by our comments, and resubmit the revised report as soon as possible.
In addition, I request that you eep Richard J. Kiessel, of my staff, advised of your progress toward resolution of our concerns and as to the schedule for resubmission of the report.
In the interim, my staff will continue with their review of the individual utility bulletin responses. Where warranted, site specific comments will be addressed to the individual utilities through the appropriate NRC regional office.
Sincerely, Original Signed by Sheldon A. Schwarta Edward L. Jordan, Director Division of Emergency Preparedness and Engineering Response Office of Inspection and Enforcement
Enclosure:
Comments about BWR0G Report NEDC-31322 Dated September 1986 DISTRIBUTION:
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e Page 1 of 4 COMMENTS ABOUT BWROC P.EPORT NEDC-31322 DATED SEPTEMBER 1986 INTRODUCTION Review of the four typical FS ARs referenced on Page 50 of NEDC-31322 is included in the scope of these comments.
Also in cl ud ed is review of the P& ids related to the typical FSARs for Fermi 2, La Salle 1& 2 and Grand Gulf I & 2.
Reviews of utility responses and procedures are not included.
R EFER ENCE United States Nuclea r Regulatory Commission, Office of Inspection and Enforcement, Mo_t_or-Operated Valve _ Common Mode Failu res During Plant Transients Due to I m p r op_e r_S_w i t c h Settings, IE Bulletin No. 85-03, November 15, 1985 COMMENT 1 The following four' assumptions are the subject of this comment:
a)
" Valves are assumed to be in and remain in their normal standby position during an abnormal event (f.e.,
the valve positions indicated in figures 1.through 8) unless the event can result in the valves changing position."
Refer to Subsection 3.3.1.1. on Page 12 of NEDC-31322.
b)
"The evaluations of the plant response to the events in Table 1 that are presented in the plant FSARs assume that the HPCS, HPCI and RCIC systems are in their normal standby condition at the start of an event (i.e.,
not running and with their valves aligned as shown in figures I through 8).
l This assumption is made because of the low probability of the system being in a test mode or out of service during the occurrence of an a bnormal event.
Consistent with this assumption used for FSAR' evaluations, the required active safety actions of the valves are established assuming the systems are in their normal standby condition at the start of an event and, hence, are not assumed to be in a test mode."
Refer to Subsection 3.3.1.2 of NEDC-31322 l
l l
Page 2 of 4
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c)
"BWRs are provided with a network of redundant systems that are separated electrically and mechanically such that, following a single failure in any system or any single operator error, adequate core and containment cooling is i
available.
The individual systems that comprise this network are not required to remain operable following a single failure in that system because the redundant systems are available to provide the required cooling function.
Therefore, a system is not required to regain operability following an operator error that results in inadvertent closing and/or opening of a valve."
Refer to Subsection 3.3.1.3 of NEDC-31322.
d)
" Valves that (a) are not required to perform active safety action during the design basis events listed in Table 1 and (b) have an extremely low probability of changing position t
during these events are exempt from the differential pressure test requirements of reference 1 (e.g., test return valves to CST)."
Refer to Page 46 of Subsection 4 of NEDC-31322 l
Assumptions (a), (b) and.(d) indicate that si_ngleequkpment failures and inadvertent equipment operations are not assumed in determination of maximum differential pressurec.
Because consideration of such failures is specifically required by Action Item a and many have been reported, we conclude that these assumptions do not meet the intent of IEB 85-03.
Assumption (c) does not comply with the requirement of Action Item a of IEB 85-03 to " review and document the design basis for the operation of each valve".
Each system should be reviewed separately, on its own merits.
COMMENT 2 I,
The following observations refer to cases of disagreement:
a)
Referring to Table 2 (Page 54) and Figure 1 (Page 67), note that no active safety actions are listed for normally closed MOVs 5, 6 and 7 of the HPCS system.
MOVs 5 and 6 are CST test return valves in series, and MOV 7 is a suppression pool test return and isolation valve.
If we suppose for example that MOV 7 were to be left open inadvertently after a test and an abnormal event were to occur, injection volume would be reduced or the isolation function would be compromised.
We feel that these possible problems should be addressed.
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Page 3 of 4 b)
Referring to Table 3 (Page 55) and Figure 2 (Page 68), note that no active safety actions are listed for normally closed MOVs 5, 6 and 7 and normally open MOV 8 of the HPCI fluid system.
MOVs 5 and 6 are CST. test return valves in series, MOV 7 is a suppression pool isolation and test bypass flush valve, and MOV 8 is an injection valve test valve.
If we suppose for example that MOV 7 were to be left open inadvertently after a test and an abnormal event were to occur, injection volume would be reduced or the isolation function would be compromised.
As another example, the injection function would be defeated by leaving MOV 8 closed inadvertantly.
We feel that these possible problems should be a ddressed.
c)
Referring to Table 4 (Page 59) and Figure 6 (Page 72), note that no active saf ety actions are listed for normally closed MOVs 5 and 6, and for normally open MOV 8 of the RCIC fluid system.
MOVs 5 and 6 are CST test return valves in series, and MOV 8 is an injection valve test valve.
If we suppose for example that MOVs 5 and 6 were to be left open in a dv er t en tly after a test and an abnormal event were to occur, injection volume would be reduced.
As another example, the injection function would be defeated by leaving MOV 8 closed inadvertently.
We feel that these possible problems s hould be a ddressed.
COU.iENT 3 In light of comments l'and 2 above, review all valves to assure l
that they are not dependent upon unacceptable assumptions.
1 COMMENT 4 In the Executive Summary on Page y and in Section 3 on Page 10
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of NEDC-31322, the statement is made that "the evaluation of system MOVs include consideration of pipe breaks in the design basi s review".
This statement should be followed up within the text.
For example, explanatory notes could be added to Table 5 (pages 63 through 65) and referenced to specific valves in tables 2, 3 and 4 (pages 54 through 62), to clearly show how pipe breaks are considered.
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.1 COMMENT 5 In order to permit detailed checking of Appendix B, please identif y the technical reference (s) on which these derivations are based.
COMMENT 6 For comparison, ref er to Table 3 (Page 57) and Figure 5 (Page
- 71) of the HPCI steam system, and to Table 4 (Page 61) and Fi gu re 8 (Page 74) of the RCIC steam system.
The following questions arise from this comparison and describe discrepancies which should be addressed.
a)
Why does steam admission valve MOV I have active safety actions for both opening and closing in the RCIC system, and have an active saf ety action only for opening in the HPCI system?
b)
Why does the HPCI system lack st eam admission bypass valve MOV IX, which is shown in the RCIC system?
c)
Why d oe s the HPCI system lack trip and throttle valve MOV X, which is shown in the RCIC system?
d)
Why is isolation valve MOV III in the P&ID of the HPCI system for Fermi 2 normally closed, instead of normally open as shown on Figure 5?
e)
Why are bypass valves MOV IV, MOV V and MOV IX not shown in the P& ids of the RCIC system for Fermi 27 f)
Why is bypass valve MOV V not shown in the P& ids o f the RCIC system for Grand Gulf?
g)
Why ar e valves MOV V, MOV IX and MOV X not used in the RCIC system for La Salle?
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