ML20151U419
| ML20151U419 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/23/1997 |
| From: | Marsh L NRC (Affiliation Not Assigned) |
| To: | Milano P NRC (Affiliation Not Assigned) |
| Shared Package | |
| ML20151U412 | List: |
| References | |
| FOIA-98-334 50-289-96-201, NUDOCS 9809100389 | |
| Download: ML20151U419 (4) | |
See also: IR 05000289/1996201
Text
.
_
_
_
e
g
g
g
1
UNITED STATES
- r
j
NUCLEAR REGULATORY COMMISSION
t
WASHINoTON, O C. 2 A6 Hoot
May 23, 1997
MEMORANDUM T0:
Patrick M. Milano, Acting Director
[hiff
Project Directorate 1-3
Division of Reactor Projects 1/11
j
.
9)
/' //,r.'is/, , . -
t
'
v
a
FROM:
Ledyard B. Marsh, Chief
'
Plant Systems Branch
'
Division of Systams Safety and Analysi's
SUBJECT:
THREE MILE ISLAND, UNIT 1 - ADDITIONAL OPEN ITEMS
ASSOCIATED WITH DECEMBER 1996 DESIGN INSPECTION
,
(SSFI INSPECTION REPORT 50-289/96-201)
1
The Plant Systems Branch (SPLB), in coordination with the Reactor Systems
Eranch (SRXB), has reviewed the two " additional" concerns identified in the
April 7, 1997 memorandum to you from the Special Inspection Branch (PSIB).
In
that memorandum, PSIB requested NRR to review 1..c two concerns and provide NRR
staff positions to be used as guidance during the followup of those concerns.
The two concerns were identified by one of the inspection team members and
,<ere delineated in the PSIB memorandum as follows:
1.
The inspector's assessment of the system impact of a letdown line failure
identified a sequence of events which merits further assessment.
The
basic concern is that failure of this line coupled (a complete line
severance is not necessary) with the postulated failure of the single
check valve that interconnects this line with the gaseous space of the
,
makeup tank could lead to depressurization of the hydrogen gas from the
makeup tank into the El. 281' area; a condition that aside from concerns
on the local explosive effects could also result in insufficient NPSH for
the high pressure injection (HPI) pumps which take suction from the
j
makeup tank prior to turnover to the borated water storage tank (BWST).
j
2.
The auxiliary steam system is also ir ated on the same elevation of the
auxiliary building as the HPl.
It i
routed in an alleyway that leads to
the HPI cubicles. However, since its complete routing could not be
observed the licensee was requested to provide design information on the
full routing of this line within the building.
The EQ impact of failure
of this system was discounted in the FSAR and in a licensee evaluation of
NRC I&E Information Notice 90-53, " Failure of Auxiliary Steam Piping"
since its operating conditions did not meet the HELB criteria of both
>200 psig and >200*F.
(The licensee concluded that crack breaks in the
piping in the auxiliary building would not result in a significant change
in the environmental conditions. Also, the HELB study concluded that the
postulated HELBs are acceptable because one string of each engineered
safeguards system would remain functional.) A review of the design
indicated that it (auxiliary steam system piping) was nonseismic;
J
typically safety analysis would include consequences of such a failure
i
during a DBA since a safe shutdown earthquake is also postulated to
g
.Q .)
occur.
'
l
i
9009100389 900904
gg yg.g gmTE COPY
QR BE 9
334
Pl*
-.-
-
,
~
.*
-
,
.
-
Patrick H. Milano
2-
The first concern postulates the random failure of a check valve coincident
with a postulated pipe break.
The staff considers this beyond the licensing
basis for THI-l and most other, if not all, operating plants.
The failure of
a che d valve is consid ed a passive failure and would not be postulated
coincident with a pipe break unless the pipe break itself could cause such a
failure of the check valve due to jet impingement, pipe whip, or other induced
mechanical force resulting from the postulated break.
Therefore, Concern
No. I should only be followed up to ensure that no postulated pipe breaks can
result in the direct malfunctioning of the check valve.
With respect to the second concern, the licensee appears to have done an
inadequate analysis of the failure of the auxiliary steam (AS) piping.
Although the AS piping may not be high energy as defined by the licensee's
criteria, it is nonseismic Category I.
Unless this piping has been
seismically analyzed to remain intact following a design basis earthquake, the
complete failure of this line must be taken into consideration, not just a
moderate energy crack.
Additionally, postulated worst-case single active
failures must be assumed coincident with the break.
As stated in NRC
Information Notice 90-53, a seismic event could result in the failure of
..rseismic Category I auxiliary steam lines.
Staff requirements to fully
break nonse'smic Category I moderate energy lines go back to generic letters
dated SeptemL=r 26, 1972, sent to each licensee,
in those letters we
requested licensees to determine (and correct if necessary) whether the
failure of any nonseismic Category I equipment (particularly in the
circulating water system or fire protection system) could result in a
condition that might potentially adversely effect the performance of safety-
related equipment required for safe shutdown or to limit the consequences of
an accident.
However, we disagree with the last sentence ef.the Concern No. 2 where it is
stated that " typically safety analysis would include consequences of such a
failure during a DBA since a safe shutdown earthquake is also postulated to
occur."
In general, the staff does not postulate a safe shutdown earthquake
(SSE) coincident with design basis loss-of-coolant accidents (LOCAs) or any
other DBA and it is not part of most plants' (including THI-1) design and
licensing basis.
Since the reactor coolant system is designed to seismic
Category I requirements, it is not expected to fail as a result of an SSE.
However, all equipment necessary to mitigate a LOCA must be designed to
seismic Category I requirements in order to ensure it is designed to the
highest standards for quality and reliability.
For the seismic induced failure of the auxiliary steam lines, the licensee
should assume a loss of offsite power (which can be caused by the seismic
event) coupled with the worst-case single active failure of any seismic
Category I equipment.
All nonseismic Category I equipment should be
considered unavailable for mitigation of this event.
However, the
consequences of additional nonseismic Category I piping system failures do not
have to be considered concurrent with the consequences from the failed
auxiliary steam piping.
The consequences (flooding, spray, temperature and
pressure effects) from failures of nonseismic Category I piping systems need
only be evaluated on an individual basis because the staff does not expect
each and every nonseismic pipe to catastrophically f ail during a seismic
=-
. _ _ -
_ . _ _ _ _ _ .
._., _ _.
__
-,-.- __
.,
_
____
_ _ _ _ _ _ _
_
. _ _
___.
.__ .
. _ _ _ _ _
_ . . _ . _ _ . _ . _ _ _ _
_ _ . _ _ _
-
e
.
.
.
Patrick M. Milano
-3-
,
'
event.
If all pipes catastrophically failed there would be no means of
transporting the fluid to the area of concern (compartment being analyzed for
pipe break) and the flooding event would be terminated after the piping within
the compartment emptied it's limited volume to the compartment's atmosphere.
If you have any questions regarding this memorandum please contact Bill LeFave
at 415-3285.
DISTRIBUTION (w/o encl.):
Docket File
,.. Central file
SPLB R/F
BBuckley
RGallo
GHolahan
CLiang
SMalur
SNewberry
RWessman
LFeFave
GHubbard
JLyons
LMarsh
DOCUMENT NAME: G:\\ SECT!0NA\\LEFAVE\\TM!0 PEN.lSS *See previous concurrence
v. r.e.tv. . e w ev int ecu ne, indie.i. in in w . c.c e i. .i
unei
w. :.ce . tin ti=wini
w. e = e. e.,
OFFICE
SPLB\\0SSA
SPLB\\0SSA
ABC\\SRXB/
BC\\SPLB\\0SSA
NAME
WLeFave*
GHubbard 8[
JLyonSY
LBMarshMl/
DATE
5/ 1 3/97
5//Y/97
5/ J'l /97
5/ b9[
OFFICIAL RECORD COPY
,
_
_ __ _ _
_
____ _ _
__.
- _ . _ _
_
_ _ .
._
_ _ . _ _ _ . . .
_ _ _ . _ . _ _ _ _ _
__ _ . . _ _ _ . . _
e
i.
.
e
,
s
Patrick M. Milano
-3-
event.
If all pipes catastrophically failed there would be no means of
transporting the fluid to the area of concern (compartment being analyzed fo
,
pipe break) and the flooding event would be terminated af ter the piping wit
the compartment emptied it limited volume to the atmosphere.
,
If you have any questions regarding this memorandum please contact Bill LeF
at 415-3285..
4
DISTRIBUTION (w/o encl.):
Docket File
4
Central file
SPLB R/F
BBuckley
1
RGallo
CLlang
a
SMalur
,
RWessman
LFeFave
GHubbard
JLyons
LMarsh
DOCUMENT NAME: G:\\SECTIONA\\LEFAYE\\THIOPEN.!SS
'
te ree.iv. . e w .t ini. 4.eu nt, i sie.i. in in. 6.. c.cor we. .tix w ir a i. w . e.cw .t in t i-wira i.-. = = = ew
i
0FFICE
SPLB\\DSSA
_
SPLB\\0SSA
ABC\\SRXB
BC\\SPLB\\0SSA
NAME
WLeFave N b
GHubbard
JLyons
LBMarsh
DATE
5/l$/97
5/-
/97
5/
/97
5/
/97
0FFICIAL RECORD COPY
J
4
J
d
'
,