UNCLASSIFIED
MINISTRY OF DEFENCE
DEFENCE NUCLEAR SAFETY REGULATOR
NUCLEAR PROPULSION REGULATOR
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DNSR/ 17/9/891
Yew 2 c
#1254 Abbey Wood
Bristol, BS34 8JH
See distribution
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e-mail:
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Date : 22 April 2010
Dear Sirs,
DNSR SAFETY IMPROVEMENT NOTICE - BABCOCK EVENT No 19720 : FAILURE TO
REINSTATE PRIMARY SAFETY SYSTEMS
REFERENCES:
A.
DNSR/17/9/883 dated 16 April 2010, DNSR INVESTIGATION INTO BABCOCK EVENT No
19720: FAILURE TO REINSTATE PRIMARY SYSTEMS.
B.
Babcock Marine / DE&S Interim Report of Joint Investigation – 12 March 2010
1.
This is a Safety Improvement Notice, following from a DNSR investigation into Babcock
Event no 19720 (Reference A), which led to the extended operation of 2 platforms with a disabled
primary safety system on a Nuclear Safety Implicated pressure system.
2.
The key failing in the sequence of events was that the BM Nuclear Procedure allowed hull
valve blanks to remain fitted after the Nuclear Procedure was closed, without explicitly including a
control to ensure their removal. However, the TXB facility operator and NRPA as joint operators
are considered responsible as those in control when the reactor was taken critical.
3.
That the information on the blanks fit was captured and then lost by all 3 parties on more
than one occasion indicates a failure of safety culture as defined by the IAEA, and shortfalls
against Authorisation/ Licence Conditions 17, 21 and 22.
4.
BM are required to amend their business processes, such that safety significant changes
cannot be introduced to nuclear procedures without an associated step to confirm that the
additional hazard has been removed or mitigated, prior to closure of the Nuclear Procedure. This
should be completed by the time of the undocking of HMS Trenchant.
5.
BM and the TXB Facility Operator are required to review their documentation to identify the
potential for other similar, open ended procedural changes, and to provide appropriate assurance
to the Regulators that the risk is appropriately managed, prior to the undocking of HMS Trenchant.
6.
BM, TXB and NRPA are required to review their procedures to ensure that key safety
information is clearly identified when transferred at handover from procedure to procedure, or PAG
to PAG. This should be completed by end of July, 2010.
7.
Prior to plant start up, NRPA as operator, and the TXB Facility Operator are required to
review the close out of their processes to assure themselves that they do all that could reasonably
be expected to mitigate the risks to plant and platform from the work completed in that
maintenance period. This should complete by the end of July 2010.
UNCLASSIFIED
UNCLASSIFIED
8.
NRPA and BM are required to present their interface arrangements to the Regulators, and to
clarify how they relate to the identification and management of safety issues in practice, by end of
June, 2010.
9.
The content of this letter has been agreed with HSE-NII.
(Signed on original)
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Nuclear Propulsion Regulator
Defence Nuclear Safety Regulator
Distribution
To:
NRPA , Cdre S Dearden, RN
Babcock Marine for the attention of Mr. Mike Homer
HMNB Devonport NBCD, Cdre I Jess, RN
Copies:
Internal External
SM IS-Hd
FLEETXXXX SM X CSOE XXXXXX
NRPA NP-Safety, XXXXXXXXXXXXX
NII Div.3 Propulsion SI, XXXXXXXXXXXXX
NBCD CBS, XXXXXXXXXXXXX
NII Div.3 DRDL PI, XXXXXXXXXXXXX
DNSR-Hd
DNSR I(CD)
Babcock Marine, XXXXXXXXXXXXX
DNSR I(OR)
Babcock Marine, XXXXXXXXXXXXX
DNSR I(CD)-a
Babcock Marine, XXXXXXXXXXXXX
File
Babcock Marine, XXXXXXXXXXXXX
UNCLASSIFIED
Document Outline
